: 96 Differential

09-18-07, 08:53 AM
Whats up fellas? I am doing some rear end work and I am changing out the gear oil, how do I know if its the limited-slip differential or not? 1996 Fleetwood Brougham

09-18-07, 10:29 AM
Sorry, no Fleetwood from 93-96 got posi/limited slip..... But to confirm, look for RPO G80 on the SPID (Service Parts ID tag) in the trunk on the inside of the lid.

BUT, to ID look for clutches between the side gears and the case for Eaton.

Auburn is OEM back then, so look for it looking like this:
http://www.auburngear.com/oemdifferentials/ for a good closeup
Eaton is OEM for older 8.5" axles like my 80 Turbo T/A.

I will put in a Eaton in mine here soon, I might get to work on the axle itself today or tomorrow. We'll have to see. I have to figure out how to get it apart, as my axle shaft on the driver's side is sooo worn I can't get it out (locked in the groove). I have a 80 Posi axle in now (not sure if Eaton or Auburn), but it is tight and fun. I really enjoy it a LOT. Very tight posi. It makes the car a dream to drive. Now I can nail the gas a lot more off the line, which with factory 3.42 and open differential was always a real problem. TC always kicked in heavy or my right tire just would spin....

09-18-07, 10:48 AM
Options to add posi easy and cheap are:
Powertrax No-Slip
OR the PowerTrax Lock-Right

BUT I don't recommend them for street driving personally. This is my person opinion from reading a LOT on these diffs is to avoid them. They are 100% locked driving down the road, and they unlock in turns. But in gentle turns, like on the interstate or so, it fights you and stays locked up. In snow/ice or wet, it will tend to stay locked and cause the car to slide sideways and break loose, almost always at the worst time.

Eaton is a great diff, it is also rebuildable. You can bias it from 200 lbs clutch force to 800 lbs. Stock is 300. I think Buick used the 200 lb setting. Off the shelf Eatons are 400 lb.

Many people really like the TrueTrac (worm gear diff), as it is very smooth diff. Even can be used in front wheel drive apps. So it will make a 4WD awesome. Not a perfect diff, but it does most everything better than all the others. Smooth, quiet, doesn't have wear items like clutches so it doesn't need rebuilding, but it doesn't do things like having one wheel in the air very well, but on the street in a car, that isn't an issue....