ID ring gear

[Bob Bridge]

I recently bought a 71 rear end with a shimmed 4:11 installed on a series 3 carrier and a 3.08 gear set originally from that rear end loose. It is a AWW housing which I read as a 3:08 that was used in several years. When I picked it up, the owner gave me a second box and said he also had a gear from a straight axle car and just in case he was giving me the wrong one, to take this along. The other gear is a 3:08 also and has the same part number as the 71's--3756448--then the 12/37 for the ratio--then GM ---then a small circle then 80 1. The pinion has been restamped and is hard to tell the numbers. The only difference visually is that the bolt holes on one are countersunk and the other is not. I have never even seen in a straight axle housing, so wouldn't know it if it jumped up and hit me. Thanks for the help

Bob

[Joe L.]

Re: ID ring gear

Bob----

I can't explain the reason for one of the two ring gears having countersunk holes and the other not. 1965+ Corvette differential ring gears do not have countersunk ring gear bolt holes and, as far as I know, 53-62 straight axle car ring gears don't, either. Really, I can't see any reason for the countersunk holes as the spider/posi case fits OVER the holes and the bolts seat on that part of the assembly. Perhaps, what you are referring to is a difference in bolt hole CHAMFER between the two gears.

In any event, I can tell you this: GM #3756448 is a 37 tooth ring gear used for 3.08:1 axle ratio gear sets for pre-63 straight axle Corvettes. It was used in conjunction with pinion gear GM #3756446. So, if both of your ring gears are GM #3756448, then you have two pre-63 type ring gears.

By the way, for 65+(including 1971)3.08:1 differential R&P sets the ring gear should be GM #3772134 and the pinion gear GM #3885941.