I just pulled the carrier out of my 12bolt covered 72 Chevelle only to find a 10 bolt carrier with 28 spline axles and a 8.5 inch ring gear. Is this common? I thought that the 12 bolt covered rear covers indicated that the rear end had a 12 bolt carrier? (you know 8.875 ring gear etc.)

Anybody have any info on this?

That is a very commom mistake. Everybody thinks that the cover bolts are what makes it a 12 bolt... There are bop rears that have the 12 bolt cover with only 10 bolt carriers. I have also been told that chevy made a 12 bolt housing with a 10 bolt carrier. I have personally never seen one though. They were to have been made in the late 69 to maybe the 71 model year and only found there way into stationwagons......

keith

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K-Star Automotive
Performance Engines
It's better to have a gun and not need it, then need a gun and not have it.

I think that one's called an Olds 12-bolt or Type O 12-bolt, reputedly not too strong & with little or no aftermarket support.

Well you were right Jimfulco. I looked at the stampings on the housing and it was R2. A little research showed that it is a Olds rear with 2.56 gears in it. They only made them from 1968 to 1970 and put them in 442's and Cutlasses. From what I read, they don't make many aftermarket parts for them, so I guess I'll have to locate a 12 bolt to replace it now.