I have a 72 cutlass supreme with a 12 bolt posi and 12 bolt ring gear I need help indentifying. The stamped numbers are CF 06 17B. There is an E stamped directly under the O . The casting number on the diff case is NF 3894939. I have checked everywear and can not pinpoint it. It is currently a 393 or 410. I pulled the cover and do not see any c clips but I am not sure what I am looking for.

Thanks
tim72

 

Sounds like a 65-67 12 bolt Chevelle rear. It is slightly narrower, about 1.325" than a 72 Cutlass 10 bolt. It will fit a vast multitude of midsize GM cars 66-72. It is much more valueble than a 72 Cutlass rear. Over the years alot of the rears have been modified or re-geared. Look to see in the center if it has 4 springs about 1" diameter keeping pressure on a clutch pack, or just a set of spider gears.

If it is a non-posi it still is worth a few hundred just for the housing, maybe even more.
Dave

 

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