Re Gearing


New member
Buick Ownership
1970 Buick Skylark
Hello everyone! I own a 1970 Buick Skylark custom and I am looking to improve my 0-60 times, so I decided that I want to change out my car's rear end. The problem is, I am a college student with a budget (preferably $700 or below). I specifically want to run 4.10 or 4.11 gears. How would I go about finding an aftermarket rear end with these ratios? If a newer aftermarket differential is hard to come by for around the price I am hoping for, which truck rear ends would work that I could probably find at a local junkyard? Is it even worth it to buy a junkyard differential? And how will I make sure it will fit my Skylark?
Thank you!


Well-known member
S.W. Ontario Canada
Buick Ownership
2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
Full disclosure... I don't know much about differential's.

But a set of new Ring & Pinion gears + labor shouldn't be more than your budget.

I've seen LSD ( not the psychedelic type ) Posi kits with ring n pinion + all the seals and bearings for about $ 700.

If you're doing the labor then definitely a Posi Kit would be the best. Having a Peg Leg is not cool.


Full Member
Staff member
Buick Ownership
Regal GS 2017
You should step back a second and give some serious thought to what your primary driving is, highway, only local roads, and/or a lot of drag racing. What is the current ratio? Not so sure you can just buy a ring and pinion without considering the carrier you current have. Typically a 3 series carrier will not accept a set of 4 series gears without an adapter. Driving your car at highway speeds with a 4 series gear set will not be pleasant to you or your engine which I may assume is high mileage.


Full Member
Buick Ownership
2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Here's a link to somewhat of what you are asking about. Unlike a Chevy rear ends it's a little more detailed on what or what not will work.
Buick Rear End Info


Buick Newbie
Buick Ownership
If you’re mostly street driven 3.73 will be a decent upgrade. I’m assuming the transmission is a TH350? Why not put a higher stall converter in it? That will help you 60 ft much better


Full Member
Oakland Gardens, N.Y.
Buick Ownership
98 Riviera, 70 GS455 Stg1
Before you even think about changing the gears, you'll need to ID the rear in the car. Some 70-72 Skylarks came with a 12 bolt Chevy rear. If that is the case, parts availability will be excellent. On the other hand, if it is a 10 bolt, then parts availability may not be so good. The 10 bolt rear in a 68-70 Buick is most likely an 8.2. It's a pretty stout rear, but no one makes gears for it. In addition, if you currently have 2.56 gears in it, you'll need to change the carrier if you want a higher ratio. It will cost way more than 700.00 unless you can do all the install yourself. If it is done wrong, the gears will be noisy. It takes some specialized knowledge and measuring tools to do it right.

It might be easier to find a complete rear with the gears you want used. A Body rears (64-72 Chevelle, Skylark, Cutlass, Lemans) will pretty much bolt in with some minor differences in track width and drive shaft length.

If you are a college student and this is your daily driver, my advice is to leave it alone. After college, if you still have the car, then you can soup it up. Some advice from an old guy who was a young guy hot rodder once and has been there done that and sometimes learned the hard way.
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