Currently I have 3 cars,

A stock 1987 Trans AM (305 engine)....with 53k original miles I just picked up, I am redoing the interior (Tan interior is not my Favorite, also using a lot of 4th gen stuff on it) and I am also thinking about changing the rear end on it.

It is stock for the most part (besides exhaust), but the rear end has drum brakes which makes me think the rear end was replaced??? I am not sure about the gear ratio (best way to tell?)

Secondly, the other 2 cars I have are parts cars...I have an 86 iroc Camaro with what I was told was a 97 trans am Posi 3:23 rear end....

I also have a 2002 Firebird, parts car, Which has the 3:08 rear end (not posi) but bigger calipers (LS1) on the back.

I guess my question is, which rear end would be better overall IYHO?

Also, Could I make the LS1 calipers work on the 97 trans am POSI rear end? (Because if I could, that would be my top choice) Please help with any advice/opinion you have....Posi worth it? or should I just put the 2002 rear end on it, less miles....better gear ratio?

Thanks!

 

If that 305 was attached to a 700R-4 rather than a T5, then I expect the 700R-4 / 305 to come with rear drums. Should be a 2.73:1 10-bolt.
3.08:1 might be the better gear for MPG, but you can put the '02 brakes on the '97 axle. Be aware the newer axles are both wider, so you can't run '87 wheels on the rear. Or you can put the 3.23:1 posi into, and the '02 brakes onto, the '87 axle. Then you can run '87 wheels. But then you need some '90-'92 axleshafts. Fortunately, the V6 versions will work as well as any of the V8 versions.
We have a whole sticky explaining all of this, which is why you got no replies.

 

Thanks for the reply, will definetely read the sticky, must have missed it. I dont plan on driving this except on weekends/nice days so I dont really care much about mpg...more about performance. I know the rear end sticks out a little more but it isnt much, the 86 camaro I have also has the spacers/adaptors for the front to make it look even. Do you know what all I need from the newer (2002 firebird) to change the calipers over to the 97 rear end? besides obviously the calipers/rotors and backing plates? I also had a friend machine me the brackets for the front conversion for LS1 brakes out of stainless steel.

Thanks again!

 

Your GM spacers are about 3 mm thick, each, while the later axles add 38 mm per side, for a total gain of 3".

 

A while back, while reading through the boards, I found a post someone made on how each read end would feel/drive/perform with the thirdgen car....I cant find it though...Could you feel me in? you seem to be familiar with all of these...like I said mpg is not #1 for me at this point...I want performance really...better take off/top end speed. Also, would changing the rear end mess up my Gauges (speedometer)? If yes, any way to correct that afterwards?

Thanks!