Editing User:Eric/sandbox/Progressive Refinements (section)

== Engine, Clutch, and Heating System ==

=== 1943-1947 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|1943
|
|020 000
|<u>Engine</u>Now: 1131 cu. cm
Formerly: 998 cu. cm
|-
|1946
|054 617
|
| [[Push Rod Tubes / Progressive Refinements|Push rod tubs]]
Now: corrugated tube ends fitted in a number of cases<br>
Formerly: with spring
|-
|1947
|071 616
|099 610
|<u>Cooling air throttle ring</u>
Now: with swing handle<br>
Formerly: slide
|}

=== 1948 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|Apr. 48
|076 722
|
|<u>Crankshaft</u>
Now: with 48.5 mm centering lug for flywheel<br>
Flywheel with a bore of 48.5 mm
|}

=== 1949 ===
{| class="wikitable"
|+
! Date Introduced
! Chassis No.
! Unit No.
! Modification
|-
| 5 Jan. 49
| 091 914
|
| <u>Heating control cable</u>
Now: twin cable
|-
| 12 Jan. 49
| 092 498
| 123 184
| <u>Oil pump cover</u>
Now: deep-drawn sheet metal<br>
Formerly: light metal
|-
| 14 Jan. 49
| 092 918
| 123 564
| <u>Air cleaner</u>
Now: mushroom shape<br>
Formerly: pot shape
|-
| 18 Jan. 49
| 093 270
| 124 031
| <u>Lower heater channel</u>
Now: modified                                                                                  thout without hinges
|-
| 1 Feb. 49
| 094 554
| 125 426
| <u>Intake manifold support</u>
Formerly: none
|-
| 7 Mar. 49
| 096 978
| 128 051
| <u>Fan housing</u>
Now: without throttle ring
|-
| 7 Apr. 49
| 100 615
| 131 840
| [[V-Belts / Progressive Refinements|V-belts]]
Now: 1 - modified stickers, 2 - new markings
|-
| 8 Apr. 49
| 100 826
| 132 017
| [[Fuel Pump / Progressive Refinements|Fuel pump]]
Now: with blue Solex diaphragm fitted with 4 seals
|-
| 28 Apr. 49
| 101 902
| 131 133
| <u>Exhaust valves</u>
Now: operating with inserted pressure plate (except for engine numbers 133 634–668)
|-
| May 49
|
|
| [[V-Belts / Progressive Refinements|V-belts]]
Now: red marks for adjusting belt tension
|-
| June 49
| 1-0 106 637
| 137 701
| <u>Vent pipe</u>
Now: extended. Modified rear engine cover plate
|-
| June 49
| 1-0 108 091
| 139 293
| <u>Filters</u>
Now: in cylinder head vent holes
|-
| July 49
| 1-0 114 186
|
| <u>Felt cone filter</u>
Now: for engines in vehicles of type 11 A
|-
| Aug. 49
| 1-0 116 811
| 147 950
| <u>Connecting rod bushes</u>
Now: widened
|-
| Aug. 49
| 1-0 117 389
| 148 542
| [[Fuel Pump / Progressive Refinements|Fuel pump]]
Now: genuine Solex in a number of cases
|-
| Aug. 49
| 
| 
| [[Push Rod Tubes / Progressive Refinements|Push rod tubs]]
Now: several hundred engines with corrugated tube ends
|- 
| Sept. 49
| 1-0 119 364
| 150 486
| <u>[[Carburetor / Progressive Refinements|Carburetor]]</u>
Now: genuine Solex, standard equipment
|- 
| Sept. 49
| 1-0 119588
| 150 702
| <u>Piston clearance</u>
Now: 0.05 mm larger for 3rd cylinder
|-
| Sept. 49
| 1-0 120 959
| 152 050
| <u>Clutch pressure plate</u>
Now: offset F & S plate. Double thrust springs continue to be used for the time being
|-
| Sept. 49
| 1-0 119 841
| 150 956
| <u>Heating control sheets, front</u>
Now: with rubber gasket
|-
| 30 Sept. 49
| 1-0 142 902
|
| <u>Cylinder</u>
Now: higher phosphorus content
|-
| Oct. 49
| 1-0 127 560
|
| <u>Clutch lever</u>
Now: reinforced
|-
| Oct. 49
| 
|
| <u>Starting handle</u>
Now: no longer supplied
|-
| Nov. 49
| 1-0 132 535
| 163 614
| <u>Heater Box</u>
Now: with straps
|-
| Dec. 49
| from 1-0 134 921
up to 1-0 134 966
| from 166 091
up to 166 135
| [[Fuel Pump / Progressive Refinements|Fuel pump]]
Now: straight push rods with conical transition
|-
| Dec. 49
| from 1-0 135 268
up to 1-0 136 157
| from 166 439
up to 167 412
| [[Fuel Pump / Progressive Refinements|Fuel pump]]
Now: straight push rods with conical transition
|-
| Dec. 49
| 1-0 136 157
| 168 075
| <u>Push rod tubes</u>
Now: only corrugated tubes with cylindrical ends at both sides
|}

=== 1950 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
| Jan. 50
| 1-0 138 646
| 169 969
| <u>Oil filler and breather assy</u>
Now: with gasket
|-
| Jan. 50
| 1-0 138 765
| 170 086
| <u>[[Crankcase / Progressive Refinements|Crankcase]]</u>
Now: oil can be completely drained off (passage through timing gear chamber)<br>
Oil quantity: 2.5 litres<br>
Oil deflector no longer required. 4th main bearing bore provided with a groove
|-
| 17 Jan. 50
| 1-0 141 601
| 173 030
| <u>Oil dipstick</u>
Now: phosphatized and blackened
|-
| Jan. 50
| 1-0 140 243
| 
| <u>Cylinders</u>
Now: gasket between cylinder and cylinder head
|-
| 16 Jan. 50
| 1-0141 236
| 172 650
| <u>[[Exhaust Pipe / Progressive Refinements|Exhaust pipe]]</u>
Now: flanges surface-ground
|-
| 21 Jan. 50
| 1-0142 442
| 173 950
| <u>Induction Tube</u>
Now: welded seam between intake manifold and preheating pipe extended on both sides by 10mm
|-
| 23 Jan. 50
| 1-0142 587
| 174 106
| <u>Distributor Gear</u>
Now: with distance spring
|-
| Feb. 50
| 
|
| <u>Oil drain plug</u>
Now: with 19mm hex. head (in a number of cases)
|-
| 4 Feb. 50
| from&nbsp;1-0145&nbsp;121
up&nbsp;to&nbsp;1-0145&nbsp;450  
| from&nbsp;176&nbsp;911
up&nbsp;to&nbsp;177&nbsp;255  
| <u>Tapped insert for spark plugs</u>
Now: with hex head (345 engines)
|-
| 17 Feb. 50
| 1-0147 713
| rowspan=3 | <u>Engine No.</u><br>181 134<br><u>Fr. Axel No.</u><br>156 350<br><u>Transm. No.</u><br>159 350
| rowspan=3 | <u>Oil Drain Plug</u>
Now: with 19mm hex head (standard)
|-
| 22 Feb. 50
| 1-0148 529
|-
| 22 Feb. 50
| 1-0149 061
|-
| Mar. 50
|
|
| <u>Spark plug wrench</u>
Now: special "Hazet 5000" with holder
|-
| Mar. 50
|
|
| [[Fuel Pump / Progressive Refinements|Fuel Pump]]
Now: only black, flexible diaphragms fitted from now on.
|-
| 14 Mar. 50
| 1-0152 857
| 185 196
| <u>[[Pistons / Progressive Refinements|Pistons]]</u>
Now: only "KS" pistons with 0.035–0.055 mm clearance fitted from now on.
|-
| 30 Mar. 50
| 1-0 156 129
| 188 974
| <u>[[Exhaust Pipe / Progressive Refinements|Exhaust pipe]]</u>
Now: 32 mm dia.<br>
Formerly: 31 mm dia.
|-
| 3 Mar. 50
| 1-0 156 970
| 188 974
| <u>Intake manifold and preheating pipe</u>
Now: light metal jacket for intensified preheating of mixture.
|-
| 15 Apr. 50
| 1-0 159 092
| 192 300
| <u>[[Crankcase / Progressive Refinements|Crankcase]]</u>
Now: push rod tube eyes reinforced and lowered.<br>
Trapezoidal section gaskets fitted in a number of cases.
|-
| 25 Apr. 50
| 1-0 161 234
| 194 696
| <u>[[Carburetor / Progressive Refinements|Solex carburetor]]</u>
Now: hinged float<br>
Float weight: 12,5 g<br>
Pilot jet air bleed: 1.0 mm dia.
|-
| 2 May 50
| 1-0 162 580
| 196 110
| <u>Automatic cooling air regulation</u>
Formerly: throttle ring with swing handle
|- 
| 9 May 50
| 1-0 164 402
| 198 222
| <u>Muffler</u>
Now: connecting tube at muffler for intensified mixture preheating (through-flow systems) is standard.
|-
| 13 May 50
| 
| 199 321
| <u>[[Pistons / Progressive Refinements|Pistons]]</u>
Now: "Mahle Autothermik" pistons fitted in a number of cases.
|-
| 16 May 50
| 1-0 168 045
| from&nbsp;203&nbsp;404<br>up&nbsp;to&nbsp;209&nbsp;190
| <u>[[Clutch / Progressive Refinements|Clutch]]</u>
Now: inner springs no longer fitted in a number of cases.
|-
| 1 June 50
| 1-0 169 355
| 203 383
| <u>Exhaust valve</u>
Now: armoured valves in a number of cases
|-
| 2 June 50
| 1-0 169 704
| 204 025
| <u>Valve seat ring</u>
Now: made of V2A steel in a number of cases
|-
| 13 June 50
| 1-0 172 368
| 
| <u>Pully half</u>
Now: inner half with spot-welded spacer
|-
| 15 June 50
| 1-0 173 695
| 207 770
| <u>Main bearing No. I</u>
Now: with outside oil groove (bearing web in crankcase without oil groove)
|-
| 19 June 50
| 1-0 173 719
| 108 481
| <u>[[Clutch / Progressive Refinements|Clutch]]</u>
Now: one spring only (standard)
|-
| 29 June 50
| 1-0 176 547
| from&nbsp;212&nbsp;437<br>up&nbsp;to&nbsp;212&nbsp;947
| <u>Oil pump gear wheels</u>
Now: remelt alloy<br>
Formerly: steel
|-
| 5 July 50
| 1-0 177 736
| from&nbsp;213&nbsp;301<br>up&nbsp;to&nbsp;213&nbsp;455
| <u>[[Carburetor / Progressive Refinements|Careburetor]]</u> [sic]
Now: without hinged float in a number of cases
|-
| 6 July 50
| 1-0 173 141
| 207 431
| <u>[[Pistons / Progressive Refinements|Pistons]]</u>
Now: "Mahle-Autothermik" pistons in a number of cases
|-
| 1 Aug. 50
| 1-0 181 111
| 217 380
| <u>[[Push Rod Tubes / Progressive Refinements|Push rod tubes]]</u>
Now: trapezoidal section seal ring is standard
|-
|10 Aug. 50
|1-0 183 539
|220 317
|<u>Exhaust valves</u>
Now: armoured (standard)
|-
|19 Aug. 50
|1-0 186 361
|
|<u>Heating control mechanism</u>
Now: hex. head screw, 9mm Formerly: slotted screw
|-
|28 Aug.
|1-0 188 291
|from&nbsp;225&nbsp;484<br>up&nbsp;to&nbsp;226&nbsp;410
|<u>[[Pistons / Progressive Refinements|Pistons]]</u>
Now: "Nüral" pistons, 75mm dia. in a number of cases
|-
|Oct. 50
|1-0 285 789
|285 789
|<u>V-belts</u>
Now: installation of 875 cable-cord belts
|-
|Oct. 50
|
|
|<u>Oil filter</u>
Now: mechanical oil filter (service part)
|-
|23 Oct. 50
|1-0 203 845
|245 131
|<u>Valve spring</u>
Now: outer spring no longer fitted in a number of cases
|-
|16 Nov. 50
|1-0 210 317
|from&nbsp;252&nbsp;725<br>up&nbsp;to&nbsp;253&nbsp;775
|<u>Exhaust valves</u>
Now: with brazed tip
|-
|2 Dec. 50
|1-0 214 450
|258 311
|<u>Distributor pinon</u>
Now: distance spring no longer fitted
|-
|Dec. 50
|1-0 218 140
|263 133
|<u>[[Pistons / Progressive Refinements|Pistons]]</u>
Now: 20 000 "Nüral" pistons fitted
|}

=== 1951 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
| 4 Jan. 51
| 1-0221 051
| 266 644
| <u>Belt pulley</u>
Now: Small modified shim, outer dia. 4 mm, inside dia. 3 mm

Formerly: outside dia.  5 mm, inside dia. 4 mm
|-
|16 Jan.  51
|1-0244 171
|270 484
|<u>Cylinder head</u>
Now: inner valve spring modified
|-
|18 Jan. 51<br />9 Feb. 51
|1-0224 763<br />20-09 940
|
|<u>Choke control cable</u>
Now: guide sleeve for thrust spring
|-
|19 Jan. 51
|1-0225 376<br />20-09 065
|272 061
|<u>[[Crankcase / Progressive Refinements|Crankcase]]</u>
Now: made of electron

Formerly: remelt alloy
|-
|27 Feb. 51
|1-0235 501
|284 793
|<u>Distributor drive</u>
Now: distance spring fitted again
|-
|21 Mar. 51
|1-0241 734
|287 661
|<u>Camshaft gear</u>
Now: made of "Resitex" plastic (for export only)
|-
|27 Mar. 51
|1-0242 600
|293 200
|<u>[[Muffler / Progressive Refinements|Muffler]]</u>
Now: modified pipe
|-
|28 Mar. 51
|1-0268 333
|from 324 902<br />up to 327 026
|<u>Valve seat ring</u>
Now: material  VCN 25 in a number of cases
|-
|6 Apr. 51
|1-0243 731
|294 845
|<u>Heat control sheet</u>
Now: front sheet relocated into heating box
|-
|18 Apr. 51
|1-0 246 090
|297 815
|<u>Generator</u>
Now: RED 130/6 – 2600 AL 16

Formerly: AL 16
|-
|April 51
|
|296 606
|<u>[[Crankcase / Progressive Refinements|Crankcase]]</u>
Now: openings (oil throwers) provided in both crankcase halves 40 x 11, right hand side
|-
|24 May 51
|1-0 253 943
|307 219
|<u>Cooling system deflectors</u>
Now: modified shape
|-
|28 May 51
|1-0 254 576
|from 307 944<br />up to 308 886
|<u>Cylinders</u>
Now: fins and deflectors inside cover plate
|-
|17 July 51
|1-0 268 548
|352 081
|<u>Valve springs</u>
Now: gradation for valve springs at cylinder head
|-
|1 Aug. 51
|1-0 272 706
|330 345
|<u>Oil breather</u>
Now: filler cap with clamp spring.
|-
|21 Aug. 51
|1-0 278 121
|336 759
|<u>Cylinder head cover</u>
Now: cover plate made of one piece
|-
|26 Nov. 51<br />26 Nov. 51
|1-0&nbsp;305&nbsp;813
20-&nbsp;019&nbsp;034
|369 483
|<u>Valve seat ring</u>
Now: valve seat ring for exhaust valve made of V2A steel (standard)
|-
|26 Nov. 51
|1-0305 813
20-019 195
|from 369 483<br/>up to 372 422
from 381 035<br />up to 382 910
|<u>Valve seat ring</u>
Now: lead-steel material in a number of cases
|-
|27 Nov. 51
|1-0306 417
|from 370 472<br />up to 370 556
|<u>Valves</u>
Now: with caps in a number of cases
|-
|10 Dec. 51
|1-0309 833<br />20-019 589
|
|<u>[[Carburetor / Progressive Refinements|Solex carburetor 26 VPIS]]</u>
Now: throttle hole diameter 1.4/1.5 mm
|-
|17 Dec. 51<br />18 Dec. 51
|1-0311 923<br />20-019 942
|376 900
|<u>Throttle ring</u>
Now: spot-welded
Formerly: screw-mounted
|}

=== 1952 ===

{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
| 18 Jan. 52
| 1-0320 113
20-020 804
|
| <u>Thermostat</u>
Now: simplified holder in a number of cases
|-
|21 Jan. 52
28 Jan. 52
|1-0320 804
20-021 054
|387 815
|<u>Gland nut</u>
Now: with felt seal to prevent loss of grease
|-
|21 Jan. 52
23 Jan. 52
|20-020 804
1-0320 113
|286 937
|<u>Thermostat</u>
Now: simplified holder standard
|-
|1 Feb. 52
4 Feb. 52
|1-0232 132
20-021 355
|390 307
|<u>Intake valve</u>
Now: induction-hardened

Formerly: surface-hardened
|-
|5 Feb. 52
|1-0323 802
20-021 398
|from 391 315
up to 359 379
|<u>Valve seat ring</u>
Now: made of lead-steel in a number of cases (3rd introduction)
|-
|7 Feb. 52
7 Feb. 52
|1-0 324 532
20-021 506
|392 231
|<u>Upper air duct</u>
Now: lateral support no longer fitted
|-
|21 Feb. 52
22 Feb. 52
|1-0 328 831
20-022 075
|397 264
|<u>Intake and exhaust valve cams</u>
Now: modified transition from surface end to radius, reduced noise
|-
|4 Mar. 52
6 Mar. 52
|1-0 338 059
10-023 584
|408 661
|<u>Exhaust pipe</u>
Now: connecting pipe between exhaust pipe and muffler no longer fitted
|-
|13 May 52
13 May 52
|1-0 352 446
20-026 314
|426 128
|<u>Pulley</u>
Now: a) pulley I, 45.0 mm

b) radial run-out: 1.0 mm

c) lateral run-out: 2.0 mm

Formerly: a) 58.0 mm

b) 0.5 mm

c) 0.1 mm 
|-
|29 May 52
29 May 52
|1-0 357 667
20-027 414
|443 003
|<u>Valve spring</u>
Now: one spring

Formerly: two springs
|-
|7 June 52
7 June 52
|1-0 360 478
20-027 952
|436 414
|<u>Oil dipstick</u>
Now: dipstick tube located higher
|-
|9 June 52
10 June 52
|1-0 360 851
20-028 063
|436 869
|<u>Fan wheel</u>
Now: balance center relocated
|-
|18 June 52
19 June 52
|1-0 364 368
20-028 709
|441 024
|<u>Crankshaft</u>
Now: thrust washer I =

0.30 ± 0.02 / II = 0.35 ± 0.03

Formerly: 1.1 – 1.2 – 1.3 – 0.9 – 0.9 mm 
|-
|20 June 52
21 June 52
|1-0 365 201
20-028 853
|418 210
418 102
|<u>Clutch operating lever</u>
Now: lever and adjusting nut with recess and chamfering
|-
|30 June 52
1 July 52
|1-0 368 508
10-029 529
|from 446 176
up to 451 092
|<u>V-belts</u>
Now: "Optiflex" material 13/8 x 50
|-
|20 Aug. 52
20 Aug. 52
|1-0 382 029
20-032 051
|462 001
|<u>Oil bath air cleaner</u>
Now: fitted in a number of cases
|-
|18 Sept. 52
18 Sept. 52
|1-0 391 619
20-033 964
|473 814
|<u>Clutch plate</u>
Now: "Textar" lining only from now on. Clutch plate 1.2 mm (formerly 1.5 mm)
|-
|23 Sept. 52
|20-034 214
|
|<u>Oil bath air cleaner</u>
Now: fitted in VW Ambulance (overhead arrangement)
|-
|26 Sept. 52
26 Sept. 52
|1-0 395 441
20-034 744
|478 493
|<u>Throttle ring support</u>
Now: guide projection for operating shaft in a number of cases

Formerly: recessed
|-
|26 Sept. 52
26 Sept. 52
|1-0 395 819
20-034 827
|
|<u>Flywheel</u>
Now: radial run-out limited to 0.2 mm
|-
|26 Sept. 52
26 Sept. 52
|1-0395 441
20-034 827
|478 493
|<u>Throttle ring</u>
Now: lever for operating rod with hole, screw head at level

Formerly: cotter pin. Screw head welded
|-
|Sept. 52
|
|
|<u>Intake manifold</u>
Now: with special jacket and jacket end (longer jacket casting). (Service part for Scandinavian countries)
|-
|1 Oct. 52
|1-0397 023
|481 713
|<u>V-belts</u>
Now: no longer included in tool kit

<u>Heating system</u>

Now: setting by rotary knob and spindle

<u>[[Carburetor / Progressive Refinements|Carburetor 28 PCI]]</u>

Now: carburetor 26 VFIS

<u>Fuel pipes</u>

Now: cross section 17 mm<sup>2</sup>

Formerly: 32 mm<sup>2</sup>

<u>Intake manifold</u>

Now: with preheating tube in joint aluminum-cast jacket
|-
|Oct. 52
|
|
|<u>Oil bath cleaner</u>
Now: two annular reinforcing grooves at the bottom
|-
|15 Oct. 52
|1-0402 111
20-036 112
|
|<u>V-belts</u>
Now: included in tool kit.
|-
|20 Oct. 52
|
|122-00 001
|<u>[[VW Industrial Engine]]</u>
Start of production
|-
|Nov. 52
|
|
|<u>Felt cone air cleaner</u>
Now: with flame guard screen
|-
|10 Nov. 52
|1-0 411 773
20-038 304
|498 719
|<u>Intake manifold support</u>
Now: beaded sheet metal strip

Formerly: pipe
|-
|10 Nov. 52
|from 20-039 360
up to 20-039 666
|from 503 889
up to 506 589
|<u>Starting dog</u>
Now: temporarily fitted in Type 2

Formerly: fitted in [[VW Industrial Engine]] only
|-
|26 Nov. 52
27 Nov. 52
|1-0 417 482
20-039 567
|505 970
|<u>Throttle ring support</u>
Now: guide projection for operating shaft (standard)

Formerly: recessed at collar
|-
|13 Dec. 52
15 Dec. 52
|1-0 423 415
20-040 811
|513 320
|<u>Intake valve</u>
Now: 4.9 dia. h 11

Formerly: 5.075 dia. h 11
|-
|31 Dec. 52
2 Jan. 53
|20-041 546
1-0 428 221
|517 651
|<u>Oil bath air cleaner</u>
Now: with strap
|}

=== 1953 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|2 Jan. 53
|20-041 712
|518 653
| <u>Intake Manifold</u>
Now: longer shaping of exhaust pipe to cylinder 3/4. Longer jacket casting

<u>Fuel piping</u>

Now: cross section 17 mm<sup>2</sup> dia.

Formerly: 32 mm<sup>2</sup> dia.

<u>Carburetor 28 PCI</u>

Formerly: carburetor 26 VFIS

<u>Clutch cable</u>

Now: Bowden cable. Clutch cable retaining bracket.

<u>Oil bath air cleaner</u>

Now: new type fitted
|-
|15 Jan. 53
|1-0433 397
|525 661
|<u>Carburetor</u>
Now: air correction jet 200
Formerly: 190
|-
|20 Jan. 53
21 Jan. 53
|1-0435 509
20-043 322
|528 095
|<u>Valve play</u>
Now: 0.10 mm
Formerly: 0.15 mm
|-
|20 Jan. 53
|1-0434 991
|from 527 580
up to 529 045
|<u>Oil pump shaft</u>
Now: shaft pressed into gear (in a number of cases)
Formerly: knurled shaft
|-
|21 Jan. 53
23 Jan. 53
|1-0435 491
20-043 414
|531 963
|<u>Oil cooler</u>
Now: position of damping plate offset (noise reduction).
Formerly: strait
|-
|13 Feb. 53
|1-0444 803
20-045 180
|539 380
|<u>Carburetor and fuel pump</u>Now: angle of nipple 40° + 5°
Formerly: 60°
|-
|14 Feb. 53
|1-0400 000
|
|<u>Cylinder head nuts</u>
Now: with sleeves, tightened to a torque or 3.5 mkg
Formerly: 3.0 mkg
|-
|20 Feb. 53
26 Feb. 53
|1-0448 196
20-046 039
|543 500
|<u>Operating rod for heat control sheet</u>
Now: left and right 217.5 and 203 ± 0.25 resp.
Formerly: 221.5 and 207.5 ± 0.25
|-
|25 Feb. 53
|1-0449 850
|545 450
|<u>Flywheel and crankshaft</u>
Now: residual unbalance market
|-
|17 Feb. 53
10 Mar. 53
|1-0446 526
20-047 157
|541 586
551 512
|<u>Clutch</u>Complete. Lobes increased from 3 to 9 (improved centering)
|}

=== 1954 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 1955 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 1956 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 1956 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 1957 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 1958 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 1959 ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}

=== 196x ===
{| class="wikitable"
|+
!Date Introduced
!Chassis No.
!Unit No.
!Modification
|-
|
|
|
| <u>Item</u>
Now: now

Formerly: formerly
|}