Engine, Transmission, and Rear End Codes

Engine Codes

Now I also have quite a few people ask me for clarification on Engine Numbers for their specific year. I have put down the main engine codes here, but there are more, I just put down the most popular. I have most of the years here from 1967 to 1981. I have listed the Pontiac 400's, Olds 403, etc. for the Pontiac Trans Ams, Firebirds, and Formulas. When looking at the engine, at a quick glance, you can notice the difference between the Pontiac 400 and the Olds 403 because the Olds 403 has the oil filler tube located at the front of the engine.

Pontiac 400	Olds 403

Where are all the codes......

On the Pontiac 400 or 455, you can look on the passenger side of the engine block, just below the heads for the engine code. And on the same side, real low on the block would be the VIN number. Now, the VIN number stamped on the engine will not be the full VIN number. It will be something like "28L111111". So, it will have a "2" for Pontiac, an "8" for the year built, an "L" for what plant it was built at, and then the "111111" would be the last 6 digits of the car's VIN number. If you look at the bottom of the engine, you will see a 400 or 455 casted into the block which can tell you at a quick glance if you have the Pontiac 400 or the Pontiac 455.

For the Pontiac Engines, here is a good shot of an engine out of the car to see it better.

On the Olds 403, on the drivers side of the block just below the heads located behind the power steering pump is the VIN number, and on the top of the engine behind the oil filler tube is the engine casting code.

Transmission Codes

 

 

 

Where are all the codes......

 

 

Rear Axle Codes

The axle code, which is a two-character code, is stamped on the front passenger side axle tube to the left of the carrier case. For example, axle code PX G70621 found on a 1977 Trans Am would be deciphered as; PX = Ring and Pinion Gear size 3.23(shown below), G = Manufacturer, Chevrolet Gear and Axle, 062 = Julian date which is the 62nd day of 1977 or March 1, 1977, 1= is the shift when built, in this case 1st shift.

 

 

Where are all the codes......

The axle code is stamped on the front passenger side axle tube to the left of the carrier case. Now Pontiac was famous for not being consistent with the location and placement of these numbers. So you might need to do a little digging and searching to be able to find the code, but it will be there somewhere. Sometimes I have seen the codes not even together in the same spot. There might be 2 numbers here, 3 numbers there.....

1967

UN - 2.56 Rear Gear (Posi)
UP - 2.78 Rear Gear (Posi)
UR - 2.93 Rear Gear (Posi)
US - 3.08 Rear Gear (Posi)
UT - 3.23 Rear Gear (Posi)
UV - 3.36 Rear Gear (Posi)
UW - 3.55 Rear Gear (Posi)
UX - 3.90 Rear Gear (Posi)
UY - 4.33 Rear Gear (Posi)
XB - 2.56 Rear Gear (Open)
XC - 2.78 Rear Gear (Open)
XD - 2.93 Rear Gear (Open)
XE - 3.08 Rear Gear (Open)
XF - 3.23 Rear Gear (Open)
XG - 3.36 Rear Gear (Open)
XH - 3.55 Rear Gear (Open)

1971

CA - 2.73 Rear Gear (Posi)
CB - 4.10 Rear Gear (Posi)
CG - 3.73 Rear Gear (Posi)
CJ - 3.42 Rear Gear (Posi)
GY - 3.08 Rear Gear (Posi)
CK - 3.42 Rear Gear (Open)
GX - 3.08 Rear Gear (Open)
GZ - 2.73 Rear Gear (Open)

 

1975

PT - 2.56 Rear Gear (Posi)
PU - 2.73 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PA - 2.73 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)
PG - 2.56 Rear Gear (Open)

 

 

1979

PS - 2.41 Rear Gear (Posi)
PV - 2.41 Rear Gear (Posi)
PT - 2.56 Rear Gear (Posi)
PU - 2.73 Rear Gear (Posi)
PR - 2.73 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PQ - 3.08 Rear Gear (Posi)
PX - 3.23 Rear Gear (Posi)
PP - 3.23 Rear Gear (Posi)
PO - 3.42 Rear Gear (Posi)
PJ - 2.41 Rear Gear (Open)
PH - 2.56 Rear Gear (Open)
PA - 2.73 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)
PD - 3.23 Rear Gear (Open)

1968

UN - 2.56 Rear Gear (Posi)
UP - 2.78 Rear Gear (Posi)
UR - 2.93 Rear Gear (Posi)
US - 3.08 Rear Gear (Posi)
UT - 3.23 Rear Gear (Posi)
UV - 3.36 Rear Gear (Posi)
UW - 3.55 Rear Gear (Posi)
UX - 3.90 Rear Gear (Posi)
UY - 4.33 Rear Gear (Posi)
XB - 2.56 Rear Gear (Open)
XC - 2.78 Rear Gear (Open)
XD - 2.93 Rear Gear (Open)
XE - 3.08 Rear Gear (Open)
XF - 3.23 Rear Gear (Open)
XG - 3.36 Rear Gear (Open)
XH - 3.55 Rear Gear (Open)

1972

CA - 2.73 Rear Gear (Posi)
CG - 3.73 Rear Gear (Posi)
CJ - 3.42 Rear Gear (Posi)
CM - 3.42 Rear Gear (Posi)
GY - 3.08 Rear Gear (Posi)
CK - 3.42 Rear Gear (Open)
CL - 3.42 Rear Gear (Open)
GX - 3.08 Rear Gear (Open)
GZ - 2.73 Rear Gear (Open)

1976

PS - 2.41 Rear Gear (Posi)
PU - 2.73 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PX - 3.23 Rear Gear (Posi)
LD - 3.23 Rear Gear (Posi)
PA - 2.73 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)
PJ - 2.41 Rear Gear (Open)
PD - 3.23 Rear Gear (Open)

1980

PS - 2.41 Rear Gear (Posi)
PV - 2.41 Rear Gear (Posi)
PT - 2.56 Rear Gear (Posi)
PU - 2.73 Rear Gear (Posi)
PO - 3.08 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PQ - 3.08 Rear Gear (Posi)
PX - 3.23 Rear Gear (Posi)
PY - 3.42 Rear Gear (Posi)
PO - 3.42 Rear Gear (Posi)
PJ - 2.41 Rear Gear (Open)
PH - 2.56 Rear Gear (Open)
PA - 2.73 Rear Gear (Open)
PD - 3.23 Rear Gear (Open)
PB - 3.42 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)

1969

ZB - 2.56 Rear Gear (Posi)
ZC - 2.78 Rear Gear (Posi)
ZD - 2.93 Rear Gear (Posi)
ZE - 3.08 Rear Gear (Posi)
ZF - 3.23 Rear Gear (Posi)
ZG - 3.36 Rear Gear (Posi)
ZH - 3.55 Rear Gear (Posi)
ZK - 3.90 Rear Gear (Posi)
ZM - 4.33 Rear Gear (Posi)
YB - 2.56 Rear Gear (Open)
YC - 2.78 Rear Gear (Open)
YD - 2.93 Rear Gear (Open)
YE - 3.08 Rear Gear (Open)
YF - 3.23 Rear Gear (Open)
YG - 3.36 Rear Gear (Open)
YH - 3.55 Rear Gear (Open)

1973

CA - 2.73 Rear Gear (Posi)
CM - 3.42 Rear Gear (Posi)
GY - 3.08 Rear Gear (Posi)
CL - 3.42 Rear Gear (Open)
GX - 3.08 Rear Gear (Open)
GZ - 2.73 Rear Gear (Open)

 

 

1977

PS - 2.41 Rear Gear (Posi)
PT - 2.56 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PX - 3.23 Rear Gear (Posi)
PJ - 2.41 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)
PH - 2.56 Rear Gear (Open)
PD - 3.23 Rear Gear (Open)

 

1981

PS - 2.41 Rear Gear (Posi)
PV - 2.41 Rear Gear (Posi)
PT - 2.56 Rear Gear (Posi)
PU - 2.73 Rear Gear (Posi)
PQ - 3.08 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PY - 3.42 Rear Gear (Posi)
PX - 3.23 Rear Gear (Posi)
PJ - 2.41 Rear Gear (Open)
PH - 2.56 Rear Gear (Open)
PA - 2.73 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)
PD - 3.23 Rear Gear (Open)
PE - 3.42 Rear Gear (Open)

1970

COF - 3.08 Rear Gear (Posi)
COL - 3.36 Rear Gear (Posi)
COT - 3.07 Rear Gear (Posi)
COV - 3.31 Rear Gear (Posi)
COX - 3.55 Rear Gear (Posi)
COZ - 3.73 Rear Gear (Posi)
CRY - 2.73 Rear Gear (Posi)
COE - 3.08 Rear Gear (Open)
COK - 3.36 Rear Gear (Open)
COS - 3.07 Rear Gear (Open)
COU - 3.31 Rear Gear (Open)
COW - 3.55 Rear Gear (Open)
CRX - 2.73 Rear Gear (Open)

 

 

1974

CA - 2.73 Rear Gear (Posi)
CM - 3.42 Rear Gear (Posi)
GY - 3.08 Rear Gear (Posi)
CL - 3.42 Rear Gear (Open)
GX - 3.08 Rear Gear (Open)
GZ - 2.73 Rear Gear (Open)

 

 

1978

PS - 2.41 Rear Gear (Posi)
PT - 2.56 Rear Gear (Posi)
PW - 3.08 Rear Gear (Posi)
PX - 3.23 Rear Gear (Posi)
PP - 3.23 Rear Gear (Posi)
PJ - 2.41 Rear Gear (Open)
PH - 2.56 Rear Gear (Open)
PC - 3.08 Rear Gear (Open)
PD - 3.23 Rear Gear (Open)
PM - 3.23 Rear Gear (Open)