how do i decode my rear end??!!

[gabes455olds]

Hi everyone,
hopefully someone can help me decode my diff. I have a 72 cutlass and I have some numbers and letters that i got from the diff. Can anyone tell me how to decode them?

J-159

1385724-F

123487890 (on driver side)

[monzaz]

You need the axle tube suffix to tell you what is in the rear diff and where it was built and the date it was built. It is usually found on the passenger axle tube facing the front of the car parallel with the ground it will have a couple of letters or a letter and a number then a space then some more numbers and maybe another letter. use a wire wheel or sand paper etc. Take a look and get us those letters and numbers and will figure it out for you. Jim

[monzaz]

The 1234567890 are test number (example stampings to compare to) they mean nothing.
1385724-F Is most likely the casting number which will tell you it is a 10 bolt 8.5 cutlas rear if it is original. I am not that great with the casting numbers. If you have a picture I know the gm rears by physical casting identification (sight)

J-159
this could be a date code of when the housing was cast J = 10th month Oct. 15 th day and 9 is 1969 ...But that usually is chevy stuff.

Jim