I have an 89 pontiac firebird formula. i need a new rear axle. Will an axle from a 98 firebird work on my firebird or does it need to be from a closer year?

 

No, a 98 axle is longer than your 89 axle. I would pull your axle and count the splines. 3rd gens came with 26 or 28 spline axles, I can't recall exactly what year it changed from 26 to 28 spline, but 89 sounds close, maybe 87. Hopefully someone who knows will chime in.

 

A rear end from '82 to '92 will fit. In '87 the ring gear diameter increased 1/8 inch and around '89 or '90 axle splines increased from 26 to 28, but they will all bolt in.

 

They are 26 spline shafts, 2.73 gears. No posi, so you guys are saying an 98 axle will not bolt in to my 89 firebird?

 

No it won't, didn't you read the posts, the 98 axle is longer than your 89 axles, plus the 98 axle is 28 spline, not 26 spline.

 

I read your post bud but missed the part that its longer. It doesnt matter if its a 26 or 28 spline tho.

 

Why doesn't spline count matter.

 

if im putting in a completely different axle it shouldnt matter right?

 

Splines on the axle have to match the carrier.

 

when you say carrier you mean the differential unit?

 

Yeah, the center part that the axle slides into.

 

my bad im talking about the rear end not the axle shafts. i have already replaced one axle shaft. I will try to get my terms right in the future

 

Oh OK, just do a "4th gen rear swap" search then. Plenty of info how. I did a 4th gen rear swap. All the info is already here, as I said, just do a search.

 

okay thanks

 

Here's a good place to start

https://www.thirdgen.org/forums/faq-...-gen-rear.html