1964-74 Pontiac GTO Engine Identification

gto_engine_hood_up

Engine Identification

1. Production Date Code

2. Block Casting Number

3. Engine Code

4. Engine Code Legend & Codes

 

1. Production Date Code on The Block:

This can be found on the distributor pad. It consists of letters A-L for month (A=January, etc.) One exception is that 1966 blocks made for 1967 model year have an M for December instead of L. The second digit or digits (there could be 2) are the day of the month. The last digit identifies the year the block was cast.

Production Date Code F129

F = June

12 = 12th of the month

9 = 1969

2. Block Casting Number:

This is found on the distributor pad for 1964, 1965, 1966, and the first part of the year in 1967. Then midway through 1967 it was moved to the back of the block behind the number 8 cylinder.

Year     CID         Casting Number
1964     389         9773155
1965     389         9778789
1966     389         9778789
1967     400         9786133
1968     400         9790071
1968     400         9792506
1969     400         9790071
1969     400         9792506
1969     400         9792968
1969     400         545887
1970     400         9799914
1970     400         9799915
1970     400         481708
1970     455         9799140
1971     400         481988
1971     455         483677
1971     455         485428
1972     400         481988
1972     455         485428
1973     400         481988
1973     455         485428
1973     455         490132
1974     350         488986

3. The Engine Code

The engine code can be found on the front of the engine block. It is stamped on the right hand bank on a machined pad. The engine code is directly below the engine production number.

Engine Code

123456
WS
22P111222

123456 = Engine Production Number (No correlation to the Vehicle VIN)

WS = Engine Code

22P111222 = Engine VIN Code (2=Pontiac, 2=Model Year, P=Pontiac Assembly Plant, 111222=Last six numbers of the car VIN)

4. Engine Code Legend & Codes

Letter Code -Two letters stamped on front of block that make up the Engine Code.

CID -Cubic Inch Displacement

HP -Horse Power

Trans -Transmission installed (Auto=Automatic, Man=Manual)

1964 Letter Code CID HP Trans
76X 389 348 Man
77J 389 348 Auto
78X 389 325 Man
79J 389 325 Auto

 

1965 Letter Code CID HP Trans
WS 389 360 Man
WT 389 335 Man
YR 389 360 Auto
YS 389 335 Auto

 

1966 Letter Code CID HP Trans
WS 389 360 Man
WT 389 335 Man
WV 389 360 Man
WW 389 335 Man
XE 389 335 Auto
XS 389 360 Man
YR 389 360 Auto
YS 389 335 Auto

 

1967 Letter Code CID HP Trans
WS 400 360 Man
WT 400 335 Man
WV 400 360 Man
WW 400 335 Man
XL 400 255 Auto
XM 400 255 Auto
XP 400 360 Auto
XS 400 360 Man
YR 400 360 Man
YS 400 335 Auto
YZ 400 360 Auto

 

1968 Letter Code CID HP Trans
WS 400 360 Man
WT 400 360 Man
WY 400 360 Man
XM 400 265 Auto
XP 400 360 Auto
XS 400 360 Man
XW 400 360 Auto
YS 400 350 Auto
YZ 400 360 Auto

 

1969 Letter Code CID HP Trans
WS 400 366 Man
WT 400 350 Man
WW 400 370 Man
XP 400 370 Auto
XX 400 265 Auto
YS 400 350 Auto
YZ 400 366 Auto

 

1970 Letter Code CID HP Trans
WA 455 360 Man
WS 400 366 Man
WT 400 350 Man
WW 400 370 Man
XP 400 370 Auto
YA 455 360 Auto
YS 400 350 Auto
YZ 400 366 Auto

 

1971 Letter Code CID HP Trans
WC 455 335 Man
WK 400 300 Man
WL 455 335 Man
WT 400 300 Man
YC 455 325 Auto
YE 455 335 Auto
YS 400 300 Auto

 

1972 Letter Code CID HP Trans
WK 400 250 Man
WM 455 300 Man
WS 400 250 Man
YB 455 300 Auto
YC 455 250 Auto
YS 400 250 Auto
YT 400 250 Auto

 

1973 Letter Code CID HP Trans
WK 400 230 Man
WP 400 230 Man
WS 400 230 Man
X5 400 230 Auto
X7 455 250 Auto
XE 455 250 Auto
XK 400 230 Auto
XL 455 250 Auto
XM 455 250 Auto
XN 400 230 Auto
XX 400 230 Auto
Y3 400 230 Auto
Y6 400 230 Man
YA 455 250 Auto
YC 455 250 Auto
YD 455 250 Auto
YF 400 230 Man
YG 400 230 Man
YK 455 250 Auto
YS 400 230 Auto
YT 400 230 Auto
YY 400 230 Auto
ZA 455 250 Auto
ZC 455 250 Auto
ZS 400 230 Auto

 

1974 Letter Code CID HP Trans
WP 350 200 Man
YS 350 200 Auto
YP 350 200 Auto
ZP 350 200 Auto