I have a 12 bolt in my 68 Cutlass and I'm trying to find put what kind it is!!!
Is there any way to tell without taking the cover off???

Thanks

 

Post pics. If it is the original, it would be an O type with a 10-bolt carrier and a 12-bolt cover.

 

The 12 bolt cover for the O= Oldsmobile mfg. diff has a smooth center with a rounded bulge outward, and is smooth and flat between the mounting bolts, and has a lip at the outer edge. The Chevy 12-bolt cover is bulged but has a big V shaped crease running from the left axle tube area, toward the center and upward, then downward again to the area of the right axle tube. This crease is used to direct diff oil toward the axle tubes and from there the oil lubes the outer axle bearings. The C cover also has a rib between each pair of the 12 cover bolts in addition to the lip at the perimeter of the cover.

 

I'll make this even easier.

Chevy 12 bolt:



Type O:



This page will also help:

http://www.supercarsunlimited.com/in...id/diff_id.htm

 

Pics coming!!!

 

5c962f77.jpg

 

Didn't see the pics!!!
Thanks Joe!!!!

 

Yeah this O type is confusing!!!
So it's really a 10 bolt????

 

Many people assume that "10 bolt" and "12 bolt" refers to the back cover. It does not. It refers to the number of bolts holding the ring gear to the carrier. Coincidentally, on Chevy 10 and 12 bolt axles, the ring gear and cover bolts are the same. Other GM axles are not that way, but in this Chevy-centric world, everyone assumes that.

Frankly, I'm not sure what's so confusing. It's a Type O, which was installed by the factory on all A-body cars from 1968-70 (except those built in Canada). Once you know that, you just need to get parts for the Type O.

 

Joe,

Don't you mean all A body "Olds" from 68-70 [except Canada] ?

 

Is there any other kind?

 

would a 1973 --98 have a O type diff? the one in mine looks like the O type.