68 - 72 A body 12 bolt from 442

[Lynn]

Have a chance to buy a 12 bolt for my 68 El Camino really cheap.
It is from a 442, coded SE 3.42 open rear (may be SF, may be 3.23... will need to confirm). Complete drum to drum.

Before I pull the trigger, can anyone confirm it is a bolt in for my 68 El Camino. Wanting to make sure the other divisions didn't have some weird difference.

I will be using it for towing from time to time, and would rather go through this 12 bolt rear and install, than go through the 10 bolt that is in it now.

Thanks for any guidance.

[Ryan1969Chevelle]

I can share that in 69 for example US made 442's had the Olds rear and Canadian made 442's had a Chevy 12 bolt.....

I have never heard of a difference other than 67 or earlier width difference.

Just Some info, not a guarantee as I haven't done it myself.

Rya

[Lynn]

So what is the difference between the Olds rear and the Chevy rear?

[marxjunk]

youd be better with the 10 bolt

the olds 12 bolt is not a true 12 bolt like you think..its a 12 bolt housing with a weird 8.5 ring gear.where as the chevelle ring gear is 8.875...and the olds is all by its self and nearly impossible to get parts for...very little support..and its weak compared to the chevelle 12 bolt

it has value to the olds guys because it came in them

demensionally its a bolt in..if its free id take it..people always confuse the OLDS and chevelle 12 bolts and when they realize it aint the same..its a bad day

[Lynn]

Thanks Mark.

[SS69chevelle]

Check the housing casting numbers, some Canadian oldsmobiles used a chevy 12 bolt in 1969, only difference is the stamp code, not sure about other years. As far as i know real Buick-Olds-Pontiac (BOP) rearends will have bolt in axles indicating it is not a chevy rearend and as mentioned is really a 10 bolt type and weaker.

[marxjunk]

after thinking about it..theres a clear identifier between olds and chevelle..its the cover...if it has a scallop on the cover, its chevelle..if the cover is nice and smooth its olds..can see it from across the street.

[Kurt S]

Yup, the cover is the tell.
It's a 12 bolt with 10-bolt guts....almost bought one years ago but a friend knew the difference thankfully.

[Billohio]

my buddy is looking for a 12 bolt for a 68 442. he explained it to me yesterday. I think he said the 67-68 are different than later because of the size of the bearing. I think he said the posi uses a bigger bearing. he was talking about having the housing bored or an insert to get something to work. sounded like a nightmare.

[Lynn]

The one here was on CL. Posted yesterday morning, and gone by evening. I didn't get additional pics, so don't know for CERTAIN that it was the BOP or the Chevy. Hope it wasn't a Chevy, or I just passed on a complete drum to drum 12 bolt for $200.

[300deluxeL79]

chev and olds 12 bolts...
http://www.yenko.net/ubbthreads/pics/usergals/2016/01/full-4800-37479-aaaa12boltchevellerearend.jpg
http://www.yenko.net/ubbthreads/pics/usergals/2016/01/full-4800-37480-aaaa12boltoldsrearend.jpg

[marxjunk]

lynn..theres always more...everyone thinks the olds 12 bolt is a chevelle 12 bolt...you'll find the right one..

i have one with 5.13s or something like that, if your really needing to pull something....like the wheels...just kidding...but i do have one with 5.13s too bad they cut the center section ears off it....

[Lynn]

I am not really looking that hard. I won't be abusing the current 3.36 10 bolt. Installing a 4L60E tranny right now. New engine is very conservative, so shouldn't be a big deal. When I do local searches on CL, there are a few "standard" I always plug in just to see if there is a deal. "12 bolt" is one of them.

[Zman1969]

Lynn. another good option would be 71-72 cutlass, skylark 10 bolts - they were 8.5", use bolt in axles (that are not tapered) gears and posi's are alot easier to find than 12 bolts
I wouldnt hesitate a bit using this rear. I have built many in the past let me know if this interests you I know where a couple are
Oh and avoid the Olds 12 bolt - hard to find parts for

[Lynn]

Thanks. I will keep an eye out, but like I said, I am in no hurry to replace this 10 bolt. I just won't abuse it.