If getting a used posi rear end for my 68 skylark, what car would be the best to go with for a close to exact fit ?
Assuming your 68 axle is the original 8.2"... Any A body 8.2" unit would swap in. BOP or chevy. Chevelle, LeMans, Cutlass, Skylark etc. More parts are available for a chevy style. Or you could upgrade to an 8.5" out of the same cars. Or a 12 bolt from a Canadian Buick. What gear ratio are you looking for?
I was considering a 12 bolt posi, or something out of a full size buick (lasabre,estate etc.), but will they fit in my 68 ? not good with all the number specs, just something i can cruise the highways with and still have a nice punch, when i hit it.
They don't fit.You have to go with the smaller cars like KenG told you.You do not need anything that strong in your Skylark with a Sbb.If you want an all around gear,330 or 342 are the best for Highway and street performance.Just my opinion on this one.BrunoD.
Hiway cruising, go with 2.73 Best combination hiway/punch 3.08 "Punchiest" gear I would use on a non overdrive car is 3.23 Just my $.02 from the ratios I have tried out.
A chevy 12 bolt is desirable, 67-67 12 bolt rears are 1.1" narrower but all mounts are the same. 2nd choice, is a 8.5 ten bolt rear, very tough.
The 8.5 is working well in our Red car. No problems. Running 3:42 gears since it is driven daily and raced on weekends. I wasn't sure if the 68 and 72 frames or rear areas were the same.
I really appreciate all the info. but what i'm really looking for in a rear end is a weekend, car show crusier, that can handle a 455 punch from time to time. No strip raceing just cruiseing. I'm beginning to think that an 8.5 is gonna be my best bet with no cutting or shortening, just an exact fit. Thanks
I believe all 64-72 A body rears will bolt in. There are some differences in width, but they are minor.
If who your buying the rear from has the original driveshaft, then it should bolt in. <!-- / message --><!-- sig -->
What is in the car now? If you aren't going to hook the car at the track, you can get by with a good 8.2. Heavy Car + 455 torque + Perfect hook will find the weak link pretty quickly. Tire spin actually puts less stress on the rear.
I'm thinking it's the original 1968, 8.2. what should i do ? I want a posi rear, that i can hit the highway on, around town car crusies and still punch from time to time. I'm thinking my best bet is to just get a basic posi rear end (8.5 or 12 bolt) and call it a day.
What is the ratio. I now have a 68-70 new positration unit for 2.56-2.93 gear sets . So if you like the ratio all you would need to do is unbolt that ring gear from your open carrier unit and bolt it to the posi and stick it back in the car. Then some reshimming left to right and your done. Pretty simple as long as you have a Harbor freight magnetic base dial indicator and some shims which I will usually supply with the posi unit. I do not know which carrier the 3.08 gears for the 68-70 rear. I need someone that has these gears to email me so we can get a measurement. posi will be 389.00
Oh, And if your street bound the 8.2 10 bolt is a fine differential. All the muscle car diffs are absolutely fine for the street. Even some track duty as long as stick shift car launches are kept with in reason 3000 and down and No Trans brakes etc. Slicks should be old for anything 1.70 and up 60 foot. The reason most rears break is because of age. Most people do not think about the rear till if fails. If these rears are rebearings and backlash reset couple thousands tighter they are fine. The posis in some of these cars are 40 years old...Stuff that is friction based can not last forever. 40 year run for a muscle car posi is tremendously good. that is 10 bucks per year for the price now. money well spent I would say for the fun you get. Jim
