I was wondering if anyone knew the exact differences in the gearing between a late third gen and an lt1 or early 4th gen? What gears and what the difference is, I'd like to know just how much a differnce it is, before I invest in a 4th gen rear end, thanks.

 

you're going to have to better define your question. like which 3rd gen and which 4th gen. v8 or v6, m5 or a4?

 

Im pretty sure my post says that, except for the v8 and auto or stick.

 

Well you have 2.73,2.77,3.08, 3.23, 3.27, 3.42, 3.45 for third gens. and I believe 2.73, 3.23. and 3.45 for 4th gens. All depends on whether its a V6 or a V8, Auto or stick. But I would go back with what ede said.

 

There are also 26 spline and 28 spline third gen axles. They went to 28 spline in 1990. All the fourth gen are 28 spline so if you're talking about an early third gen diff, there are even more differences. The third gen diff also changed from a 7.5" ring gear to a 7.625" ring gear around 1986 so again, there's even more differences. The brake system has drums, old style disk and new style disk. There's also a third gen 9 bolt diff and a Dana 44 was available through the GMPPC. Gear ratios depend on the exact model of the car. Depending on what engine and tranny was offered will determine what gears were offered for each. There is no distinction between a V6 or a V8 10 bolt diff except for gearing but even then a V6 car could get the same gearing as a V8 car depending on options.

If you're not going to be specific about the diff, you're not going to get any correct answers.

 

he said he thought his his post was pretty self explanitory so it looks like he can't narrow it down any better, except for the v8 part and some how we should of picked up on the v8 thing when he said 3rd gen and 4th gen since everyone knows the v6s don't count.

 

Alright, this is about as specific as I can get, I would like to know the differnece between my gears (3.27) and the gears in the rearend of an early 4th gen LT1 automatic rear end, any info would be appreciated.

 

Ahh. 3.27 gears. You have a Borg Warner 9 bolt diff. It's far superior to a 4th gen 10 bolt diff however parts are expensive and hard to find.

The web site is a little outdated but go here to see how good a 9 bolt is
www.diffsolutions.com

A 4th gen diff is a wider diff than a third gen (about 2" on each side). It has 28 spline axles and a 7.625 (7-5/8") ring gear. Same as the 1990-1992 third gens just wider.

 

Early Auto LT1 could have 2.73's or 3.23's. I'd stick with the current 9 bolt