Hey guys, I have a few questions for your Chevy gear heads. Siince i dont know much about GM cars and trucks myself. My brother has a 1968 Chevy Chevelle/Malibu. He is getting a new crate motor for it. And since the car is out of commision for a few weeks, he is thinking about go from a 10 bolt to a 12 bolt. 12 bolts are kinda hard to find, from what i have heard. Is there anyway to make the 10 bolt a posi? Or would it be worth it to get a 12 bolt? And if the 10 bolt will work with a locker or such, how durable will it be? He will be putting about 450+hp to the rearend, so will it hold up? Thanks in advance, and sorry for the long post.

:D

Anyone? TTT

i've seen several 10-bolts blow up at the race tracks, i've also seen some w/ spools, 4.10 gears, and strange axles hold up to 500+ hp, now unless u want to drop about $2000 into that 10-bolt, i have a 12 bolt housing for sale for really cheap, u can get new custom shafts or use the one's with it, it does need new gears and a new carrier

I dint think that 10 bolt is worth putting the cash into if he is going to run 450 HP. Find a 12 bolt or build a 9 inch.

A 10 bolt can be set up w/ any traction divice you can get for a 12 bolt & use the same 30 spline shafts. The pinion shafts are the same 1.625" dia.
The only strength difference I can see is a 3/8" bigger dia ring gear.

housing is stronger, and the stock carrier is stronger in a 12-bolt, the shafts are a little bigger also, we compared them

Thanks everyone for your info and help. I think he is gonna go with a 12bolt and go from there. Thanks again!

I would go to your local junk yard, pull a 9" out of a Lincoln complete with disk breaks, posy, ext. cut and weld on new shock and spring mounts and you would have a rear end that could hold 450hp eazy. And say you add a blower or nos later just put strange axles and gears in it, there only 100 bucks a pop for axles and 120 for a gear set. You also have your choice of limited slips, lockers or spools.

Start looking for Pontiacs from 67-72. Should bolt in and it seems that most got a 12. My 70 LeMans is a base model with a 350. It was optioned with "Safety Trac" (Pontiac Posi same as Chevy Posi). It has a 12 in it. I think any of the v8 Pontiacs got it because all those cars were Big block. Quit thinking chevy. The 350 Poncho block is the same block as a 455. Just not punched out to it.

I blew the factory LS 10 bolt in my 66 GTO after putting a built 455 in it. It ran a minimum of 450+ hp and 550+ fp (calculated, never on a dyno). Next up was a LS 12 bolt (complete with sway bar) out of a 71 Chevelle SS 454. It is a direct bolt in with no mods. That held up fine till I started running "street slicks" on "grudge night" at the local track. Finally I was "hooking up"! Then it blew a spider (I think) after about 5 passes and lunched the case. Found another 12 bolt, that one lasted about a month of daily driver and track use (ran the street slicks at the track). Moral of the story is, IMO, no way will the 10 bolt stand up without major mods, and a 12 bolt will need some upgrades if you expect to thrash it in a heavy car with allot of hp/tq.

10 bolts can have 28 or 30 spline shafts & carrier. Your car would have 28 spline. I don't think they came out w/ the 30 spline stuff until the late '80's. If you keep the 10 bolt, get a 30 spline posi or whatever diff & have 30 spline axles made. Then you have the same shafts as a 12 bolt. It may be more involved than that. Probably different bearings.
The housing & carrier may still be stronger in the 12 bolt. I would recommend getting a 12 bolt if you can. I got the one in my S10 for $500 w/ 4.10's & posi. It was out a '70 Chevelle.
Jegs sells a "Pro Race Axle Package" for $616. It includes 33 spline shafts & spool, c-clip eliminatos & stud kit. Part no. 873-P-2000. www.jegs.com