okay so heres my problem...i want a rearend that is more common and stronger for my 68,it has the original 12 bolt type "o" rearend...code is "sa" so i know its an open 2.78 peg leg smokebomb rearend. ive looked into rebuild kits and ive found little to none. i know its a non c-clip rear which is nice but im afraid of blowing the thing up because i plan to put a fair amount of power to the wheels and would like something strong and more suited for what i plan for this car. i know ill catch heat from the diehards around here but its my car right? so i put this out there....i am looking to trade straight up my type "o" for a gm 12 bolt from a 68-72 chevelle...doesnt matter if its a peg leg cause i will have it built up but i also want it to be a functional rear...in other words i dont want to open it up and find broken stuff cause i wouldnt do that to you. so if anyone is within 50 miles of simi valley,ca.93065 and you are interested then of course post a response or email me through the site.

 

I had the same rear end in my '69 Delta and wanted to get some steeper gears, never did though. To be honest, I don't think those are weak rear ends, have never heard of one blowing up or failing. With 2.73 ratio they were made for the highway cruising and handling the torque from even the BBO's. But like you said, it is your car and you should do what you want. Maybe you should look for some steeper gears while you are at it though, that would improve the acceleration and performance feel in your car. Just a thought.

 

What Dan said is true. And you can get gear sets for Ch#vy axles at Wal-Mart. OK...maybe not there...but they are much more available than Type-O.

If you've read my posts, you'll know that I am an Olds man...but if you are reeeeeeeeeeally putting down some serious numbers, a Ch#vy 12 bolt is the way to go. Get a set of c-clip eliminators and you can safely pull a stump. To pull a house, you'll want some Moser-type axles.

C.J.

 

I think you'll have a hard time getting a Ch*vy 12 bolt for your Olds rear, they're getting really hard to find. An option to consider would be the newer corporate 8.5 10 bolts. They started using them in mid-year 1971 through 1972 Cutlass. I've been told the guts from the corporate 8.5 interchange through 1988 1/2 pickups and vans. Lots of parts available for the 8.5 and much cheaper than the 8.75 12 bolts. Many years ago Supercarsunlimited in Portland Oregon showed me a twisted off axle from his quarter mile car. It was an 8.5 corporate 10 bolt posi. So the torque of the engine twisted off the axle but the gears handled the torque just fine. Something to consider.
John

 

I guess it depends on where you are...Ch#vy 12 bolts be plentiful down here!

I have a 72 parts car with an O-type 12 bolt 3.08, but gears are what's REALLY hard to find. I'm currently running an Olds 10 bolt with 3.42 posi. My builder (an Olds racer) says it will do just fine behind the mid-12 second street/strip 455 he's building me.

Talk to California Differential in Fremont. They have a good rep.

C.J.

 

Try "Rear End Specialties" of Sant Clara.......... great place
Digiulio ave, Santa Clara 408-988-3619

Gene

 

i dont know how much you plan on spending to do your rebuild, but you can buy a brand new 12 bolt from strang and mosier. these are not rebuilt gm rearends.they are completely brand new without brakes for bout 2k.yes expensive but supposed to be like 40% stronger than gm rear and with aftermarket axles,gears, and posi or spool.

 

Keep in mind the '70-'72 Monte Carlo rear ends. I've heard that just about every one of these cars that originally came with a 4 bbl V8 (sbc OR bbc) also came with a Chev 12 bolt. Since it's a direct swap for the Chevelle, I imagine it's a direct swap for the Cutlass. That's both good and bad; many of these Montes have already been picked over for their 12 bolt rears by the Chevelle guys (I was once one of the Chevelle guys - please don't judge me by my misguided past! )

- GoldOlds

 

Yeah, good luck with that. I'm sure some Chevelle owner will jump on the opportunity to trade his stronger, more popular axle for your orphan Type O.

Besides, Type C 12 bolt axles for A-body cars are getting to be priced out of reach of mere mortals. And before you jump on the 8.5" Corporate 10 bolt, just remember that other than parts availabilty there's no advantage. Also keep in mind that Type O axles are retained at the outboard ends, so you don't need to install C-clip eliminator kits. I suspect that if you total up the cost, it will likely be cheaper to keep your Type O. Parts (posi carriers, gears, etc) are available here:

http://www.drivetrainspecialists.com...ile/index.html

 

well its been a while since ive been to this site...but getting responses and feedback to my questions has raised me from the ashes...alot has happended since my recent divorce...she said me...or the car...well she already drained my bank accounts so i chose the car...she is in pieces but progress is promising...ive decided this...fab 9 rearend as yes i will be tubbing and putting some decent horsepower to the ground so why not.the body is off the frame and the frame is being boxed and every weld gone over and every weak spot made strong...body is being rid of rust and dents and the car will be on a healthy diet of fiberglass any where there is a panel available...i hope to be campaigning the car in the pacific street car association by mid next year so look for a very mean 68 442 soon at the tracks taking on those pesky mustangs

 

Too bad ... You can keep your 9" rears. Off center sheet metal housing. I am sure it is a nice rear from Currie. Just do not want anything with FORD on my cars. Just an opinion. Bias opinion at that...lol

Good luck with it. Jim J D Race

Oh and on the 8.5 not being a upgrade from a 12 bolt 'O'...That is wrong....It is much better upgrade. the yke spline and pinion is completely different and larger...Built like a 12 bolt. Easy to upgrade to 30 or 33 spline axles also .

Just some more info.

If anyone is interested in restoring your 12 bolt 'O' type rear I can help I ahve been collecting posis and some gears and can help get the best prices i can get to you guys. Just ask. There is NOTHING wrong with the 12 bolt 'O' type rear or any 10 bolt for your high torque street pounder. It will handle the street with no problem. It is when yo start 4000 stal trans brakes etc. when your going start having trouble. They will more than take the slicks also as long as you are not gonna bracket race every weekend. At a show here and there your cool. Jim

 

FYI,

My 72 Monte had a 10 bolt..Not 12..

However, I did finally put in a Ford 9" with 3.90 limited slip to meet up with the 383 Stroker and 700R4....

Great combo!!!