I found and wrote down the code numbers and letters on the 10 bolt rear end that I'm considering pulling from a donar car. Problem is that I cannot find the exact matching number and letter sequences in my ref. material. So here goes, hope you can help.

Donar car: 1987 GTA
Axle code from passenger side tube: 4HJ C 1042.
RPO code GW6, G80
10 bolt, posi

Maybe you can help me decode it?

Thanks!

 

4HJ = 3.23
C = Buffalo assembly plant
104 = day of year
2 = night shift

If it's a posi, there should be an E at the end.

GW6 = 3.27
G80 = posi

Looks like the car originally came with a 9 bolt posi with 3.27 gears and someone installed an open diff 10 bolt with 3.23 gears.

Only way to know what's really inside is to pull the cover off and have a look.

 

Thanks Stephen 87 IROC.

The last alpha digit I wrote down was Z, which I omitted from the original post. I'm wondering now, if it should have been an E... will need to check it again. I did rotate the drive side axle forward and also in reverse directions. The passenger side axle turned in the same direction as the rotated axle which I assumed then that it had a limited slip carrier. As you mention, the only real way to confirm open or posi will be to remove the end cover.

Thanks for the reply.

 

A 3.27 9 bolt will have 4EU stamped on it plus will have 9 bolts on the cover. Since you say it's a 10 bolt, it's obviously not the original diff.

Since the diff has been swapped, you'll never know what's actually inside unless you pull the cover. Even the gear ratio can be different than the code. You can only assume it was a direct swap with nothing changed inside.

 

oh!

so 3.23 is 10 bolt ratio ?!

oops i thought it was one of the 9 bolt ratios lol...

i didnt think 3.23 was a GM ratio.

hum

interesting.


thanks!