I am looking to buy a GTU rear for my convertible to improve performance.I have found one on the internet but the seller does not have the donor car and cannot tell if it is from a GTU. It does have 4 piston brakes and it says LSD on the diff drain plug. Does that mean it's from a GTU and has the final drive ratio I'm looking for?

 

I was under the impression that none of the rear ends had 4 piston brakes.

 

It sounds like the seller has an 88 GTU rear (clutch type L.S.D. and 4.1:1 gear ratio).

If you want the 4.3 gears, then you want either an 89 or 90 GTUs rear end. You can also buy the ring and pinon from places like www.rx7.com, but they are pricey.

Your profile says you have a 91 vert, and I think those came with 4.1 gears already. The S4 verts came with 3.9 gears.

 

Yeah, on any 89-92 vert they had the 4.1 rear end anyway. so you would only be adding the LSD (which in most cases of less than 200hp no one notices anyway).

Only the 88 would gain any performance

 

My Car is a '91 so nothing to gain. Thanks for the education!