I've been preplexed by this for a while now, here's a picture of my rear-axle. I think it's pretty clear it's not a Borg-Warner axle. But I'm pretty darn sure I got a 1991 GTA because I went through alot of trouble to verify it via third parties and they said it was a GTA(lost RPO sticker and no front decal). One made for the european market.

My car also has rear disc brakes and not drums, apparently it also has an aluminum drive shaft! The RPO code JG1 is present as is Y84. The code G80 is aso present which I think means it's a Borg-warner? Or not?

Can anyone help me? Am I in possession of a GTA or have I been really hoodwinked? I mean the seats, the trim, rear disc brakes, the RPO codes that checked out via third party...

Here's my VIN and RPO code if it could help anyone identify it:
1: U.S. Built
G: General Motors
2: Pontiac
FW: Firebird Trans Am
2: two-door hatchback/liftback
3: active (manuel) belts w/driver inflatable
8: L98 - 5,7 V8
8: check digit
M: 1991 model year
L: van nuys ca
201417: production sequence

RPO-Codes:
AAA AJ3 AU3 A31 A90 BC8 B2L B84 C49 C60 DC4 DD9 D42 D5X D8F D81 EXP E5Z E9Z FE2 GU5 G80 IL2 JG1 J65 KC4 K34 K68 L98 MAE MD8 MX0 NA5 N10 N64 PW7 QLC T96 UB3 UL2 UQ1 UX1 U19 U62 U75 VAN VC5 VK3 V78 WS4 WS6 Y84 19I 19Q 192 199 41U 52P 6ZX 7ZX 8NL 9NL

 

The 9-bolt was discontinued after 89.

Be glad you don't have it: if you did, it would be older than your car, and would indicate that it had been swapped in.

G80 means it came with a posi; not a 9-bolt.

 

Oh I didn't know that. So things are looking good then again. And having an aluminum driveshaft according to my RPO... Thats a one heck of a positive suprise (interested in loosing some weight)

 

By the way, if I where ever to require a change of the rear-axle, would you reccomend swapping in a 9-bolt over a 10-bolt?

 

10 bolts are cheap and plentiful. 9 bolts are marginally stronger and parts are expensive and harder to find. benny

 

If you can find a 1989-year 3.45 or 3.70 nine bolt in good condition, then its worth it. 1989 was the only one with the better brakes that the 90-92 10-bolts have.