GTMeach

I have heard California built 442's in 66 came with 12 bolt rear axles ( 12 bolts as in cover bolts, not necessarily ring bolts)

joe_padavano

Oldsmobile started using the Type O axle under the Cutlass line in May of 1966. The Type O has a 12 bolt cover but only ten bolts holding the 8.5" ring gear. It is not a "12 bolt" and no Chevy 12 bolt parts will fit. This was not a function of being built in California - Lansing cars were first.

All Cutlii built in CANADA for 1968-69 DID get the Chevy 12 bolt in place of the Type O, however.

GTMeach

Thats interesting..my car is a late May 66 build and has a 12 bolt COVER. Is there any casting, or stamped dates on the rear ends?

joe_padavano

Which is consistent with when Olds started using the Type O axle. All assembly plants did this, not just Fremont. You won't find any info in the Chassis Service Manual since that manual was printed in Oct 1965. There is a dealer service bulletin from May 1966 that talks about this.

GTMeach

The julian date on the rear is 170. My car was built 05D. Doesnt work...UGH

66-3X2 442

Why doesn't it work? That's the last week of May which would be in the 180 range.

GTMeach

Thats end of June

66-3X2 442

My bad,sorry.