Was playing with the idea of swapping out my stock non posi rear out of my 1971 Skylark 350. Was thinking of going to a posi and found a 1970 Buick Skylark 10 posi with 3.08 gears for sale for $400. It is a direct swap? Is there any benefit other than the obvious and is $400 a good price. Opinions welcome!
Should be a direct swap, and yes, $400 for a complete posi rearend is a very good deal if it's in good shape.
If the posi in the 1970 is original then it is an 8.2 which is more difficult to get parts for as opposed to the 1971 and up 8.5 units. Read this info on George's website: http://www.buickperformance.com/85rear.htm
It will bolt in BUT since you had a 8.5 10 bolt in the 71 the 1970 pinion shaft will be shorter and require A longer drive shaft by about 3/4" 1971 1972 8.5 rear have a lot more part available PLUS it is your original rear end and 3.08 gears are extremely plentiful in the 8.5 I have a set for 50.00 and the posi unit are still very get able in a lot of yards. So basically if you get a longer drive shaft you will be fine. Jim
Really would like to keep things as simple as possible. So for now I guess I'll stick with what I got until I find an exact swap.
Depends on who you have set up the posi. I can get you one for 389.00 3 series unit. vIf your not swapping out gears it is usually pretty straight forward set-up as the pinion depth does not change so the hard part is done. Jim
1971 1972 BUICK SKYLARK or OLDSMOBILE CUTLASS ONLY. that is all that will be a DIRECT no mod swap. Jim what is your price range for a rear diff? Have you done any engine work etc? Jim
There were 2 different 8.5 posi unit in the day 1970 1971 1972 1.) trac lock GM unit clutch style with the 'S' spring LSD (posi) came in 2 or 3 series carriers meaning 2.41 -2.56 (2 series) 2.73-4.56 and beyond( 3 series) 2.) Borg Warner/ Auburn cone type unit LSD (posi) came in 2 or 3 series units same carriewr breaks of course. reference pictures for I D TAke care. Jim
Ok I understand the low ball on the rear diff pricing then...lol. I always run into people that spend thousands on a motor and even 1-2 thousand on a tranny but when they get to the rear they just throw a use rear in...lol. You have a good base you should just build the rear you have posi and some gears and a rebuild kit. 279.00 factory posi 79.00 rebuild kit 3.08 or 3.42 new gears 149.00 150-200 set-up at a rear diff joint 700.00 you have a good strong diff to last a while...plus it has exactly the ratio you want. :3gears: :3gears: :3gears:
In other words is it better to take my stock non posi and convert it to posi? Sounds good as long as there are no issues! The rear I have now is fine but I thought the posi and a trans reporogramming kit would give me a noticeable bang for the buck.
Issues. Everything fits into the 10 bolt 8.5 open housing. Open or posi housings are all the same. 28 spline axles.
Thanks for the info Jim. If I decide to go that route I'll be in touch! Just replaced the wheel cylinders and brake set ups on both sides so I would most likely keep what I have and work with it. Just need to get the funds together to get the work done after getting the parts. Not confident enough to do the gut swap on my own.
If you have the rear out of the car is really is not that bad. I have help quite a few guys with the set-up on line. Just need patients and a few tools (dial indicator and set-up bearing) fairly cheap stuff. Jim
Steve, Since you are in Clermont....get over to LKQ on SR50 just east of Orlando....many of the GM full size wagons from 81-87 have the 8.5 posi rears in them......I have an article on our site on how to find and remove the posi units. While you have the rear apart....put in new bearings and seals and you will be set.
I do not wish to hijack this thread, but I have a question for MONZAZ. I was looking at this >> http://www.summitracing.com/parts/DTL-913A555/ for my 69 GS 400. I have an open 12 bolt rear, with 3.07 gears. Will this fit? It's a true 12 bolt from Canada.
