I just figured out after talking to a parts guy at my local Pontiac dealership that the rear end in my 85 Trans Am is apparently Australian. The difference, as explained to me by this parts guy, is that its 7 3/4, versus the 7 5/8 that was stock in Canada and the US, apparently. However, that's all he told me. I know it can handle more power than the 7 5/8, but does anyone know off hand what exactly it can handle? I'm planning on putting a crate 350 into her once all the safety work is done, and I'd like to know if this rear end will be able to handle roughly 400hp.

Thanks.

 

The "Australian" rear end is the 9 bolt Borg Warner. It was stock in the US and Canada.

 

I didn't think it was stock in the '85 year though.
If the cover has 10 bolts it's the 7.5" or 7 5/8", if 9 bolts, 7 3/4". Only bad thing about the 9 bolt is the parts for it are harder to find.

 

the parts for the 9 bolt are def more money BUT on the good side the 9 bolt is supoose to be alot stronger than the 10 bolt. how much power it can handle before it blows I don't know, but I have a 9 bolt in my 84 T/A (not original of course) and in the car is my 383 motor and the rear end hasn't ever had a single problem. I have done the burnout contest at the Car Craft show here in July every year a few years in a row without a hitch. I wouldn't have any concerns in putting in a 400hp 350.

 

It was available in the T/A in 1985.

 

Yep, optional in 85-89 in Trans Ams and 87-89 in Camaros. Also a very few 1990's that were using up the old stock of 9-bolts.