Numbers on ring. 3910 GM 9 66 PA
Numbers on Pinion. 39 10 GM 1 67 ED

Thanks

 

The 39 10 is usually ring to pinion count.
Giving you 3.90 to 1
Other #s I don't know

 

They are Pontiac gears

66 and the 67 are the years - They probably are a matched set and are most likely from the 1967 rear end housing.

10 pinion tooth count
39 ring tooth count

The letter code PA and ED are factory guru codes they mean something but not figured that out yet. Sorry even I do not know EVERYTHING about ring and pinions.

This for a 10 bolt 8.2? 10 bolts on the ring? 27 spline pinion

 

Thanks for the info guy's. I bought a bunch of parts off a 67 442. The guy went total race with the 400 in it, so all the stock parts were just sitting there. Intake, exhaust, crank, oil pan, ect: He went with 411's but wasn't sure what theses gears were. I'm thinking they wont fit my 67 posi rear with the 3:08 gears?

 

Yes. 10 bolt ring, 27 spline pinion.

 

Yes the 3.90 can fit the carrier you have with a spacer plate about .150-.200 thickness will work. in a pinch 10 bolt 8.5 shim can work BUT you will need to get the 3/8 inch longer bolts bought separately. Jim

JD

 

Tom, what you will have is a 2 pinion carrier, though. Most of the '66-'67 carriers that take the 3.55+ gears are the 4-pinion carriers and they are stronger units that what you have.
Just something to consider, depending on how how strong you want the rear to be.