[logan__tille]

Do they make such a thing? If not, How could I make my rear end posi instead of limited slip? Sorry If i sound like a stupid ****** lol but im new at this stuff.



EDIT: masked profanity is not allowed here at HR

[speedydeedy]

First tell us what rear end you have.

[logan__tille]

Well, i'm really not sure. Do you know where the serial numbers might be? The car is a 1977 Oldsmobile Delta 88.

[speedydeedy]

I don't know but if you look in JEGS you can usually tell by the shape of the rear cover and # of bolts. As in a GM 10 bolt 8.2". Look at the POWERTRAX they work well and are easy to install.

[logan__tille]

Alright. Thank you.

[JonRunaas]

"Make my rearend Posi instead of Limited Slip"... um, I think those are the same thing. Positraction is just a catchy brand name for limited slip. I think you meant going from an "open" differential to a limited slip/posi. As far as how to put it on your Olds, you just have to buy the differential and get it installed into the rearend (I've been told is not easy to do yourself). I'm currently looking to do the same thing for my 78 Impala and from what I've been advised and the research I've done, it looks like the Detroit Truetrac seems to be the best bang for your buck. Summit sells them for lots of different axles, check it out! Just a few weeks ago I started a thread on almost the same topic, and got lots of great advice. Check it out: Rearend rebuild advice

[jimfulco]

You have either a 7.5" or 8.5" GM rear end. Both were found on late-'70s GM B-bodies, and it's easy to tell them apart just by looking under the car from the rear. There are projections on the lower portion of the case at the 5:00 and 7:00 positions that are a dead giveaway. Go to http://www.oldsmobility.com/10bolt-tech.htm and scroll down to the pictures.

Some people might tell you the wheel bolt pattern will tell you which you have, but that's not true. Both patterns (5" and 4-3/4") could be found on either size rear end.