[A.W.Dille]

I found the original build sheet for my GP today above the headliner board. I'm curious as to what wheels were coded TW, color code of what appears to be I9 and the rear axle code of 9AJ. The rear end is original to the car right now. Just curious as if anyone has information on deciphering these codes. Thanks in advance. Alan

[Lightfoot]

Good to hear you found it.
That is the first time I ever heard of one being in that location. Makes me wonder how common that was, and if it started during a certain year after the down sizing.

What plant was your GP from?

[A.W.Dille]

Haven't been able to locate that information on the build sheet. It's gotten kinda brown but overall in good condition. As soon as I figure out how to scan and load I'll try to get a copy on here.

[Mr Twister]

My wheels are also coded TW, They were black 14" steel wheels with fake wire wheel covers. Can't help with the axle. I also found mine above the headliner, strange spot for sure.

[A.W.Dille]

Thanks, yes it was a strange spot for sure. Found another sheet hog ringed to the framework of the back seat bottom when I pulled it the other day. Haven't been able to cut those yet to see what info it contains. Want to keep all the original paperwork I can as this is the first time I've found the build sheet in any Pontiac I've owned. Even though I'm going to replace the rearend I am still curious about the gearing, but may pull the cover off the housing and change out the grease as I'm starting to get some backlash in the gears. I'm surprised the 7.5 has held up this long behind a 400 and now 350 Pontiac.

[Mr Twister]

I have a rebuilt 8.5 Grand National rear in mine. We put 3.73 gears in it and an eaton posi.

[Lightfoot]

I'm gonna guess it is either a 2.41 or 2.56.
It probably depends on whether it was a 231 or 305. My 1980 Lemans had 2.41 with the 229 V6. I think that was the first year they put a 'lock-up' converter in the trans. Not sure what transmission upgrades took place between then and 1985.

[A.W.Dille]

Mine originally had a 3.8 (231) and had the 200 Metric trans with lock up converter. It could be one of those gear ratio's, but seems a little steeper than that. My plan is an 8.5 with 3.55 gears. With the 275-60-15's I've got on the back of it now should offset some of the increase in the gearing and I like it better with the Turbo 350 that I have in it right now behind the 350 than I did the 2004R. Once I get a carb set up for it this thing should be a bout as quick as my GTO.