Corey_68

I have a couple rear ends, both thought to be original but not sure what model year?

gbvette62

"AY" is a 2.73 rear, "W" is Warren (where it was assembled), 331 is the Julian date is was assembled (the 331st day of the year), "E" is Eaton, the maker of the Posi unit and "2" is the plant shift it was assembled. I believe "AY" was only used in 75.

"AW" is a 3.08 rear, assembled at Warren on the 55th day (055) of the year using an Eaton Posi on the second shift. "AW" was the code for 3.08's in 71, 73, 74, & 75.

Corey_68

Thanks G, I think the second diff came out of a '71 Big Block.

Much appreciated sir.

Tuna Joe

Corey,
any interest in selling the differential cover for the 71?
Curious what the casting date is. I need an early 71. Prior to March 71
Thanks

Joe

GTR1999

273 were an option from 69- mid 70's, not many were built.
308 very common, just about all C3 automatic cars were built with 308, some 355

Corey_68

Hey Joe, It may be going into my '68....I'll keep you posted.

Corey_68

Thanks Gary, that's good to know.

Now the dilemma... the 2.73 rear is current installed in my '68 which now has a mildly modded LS2 and 6 speed manual (double OD). I assume over the years the original '68 diff blew ( my father owned a restoration business/speed shop) and installed another diff he had laying around. I didn't feel any lack of gearing with the torque of the Big Block I had installed. In the current set up at 70mph I'm turning 1350rpms, but I can hear the radio and hold a conversation with the passenger. I don't race it, but also know how much fun the 3.73s were in my other car. Hmmm

Being that none of gears the sets outside of Tom's is American made anymore, would I be better off trying to find another diff with the original gear ratios that I want or have it rebuilt with new (likely foreign) gears?

GTR1999

Rather than relying on housing stamping, especially on a used diff, open it up and confirm what you have.

There are no new usa made gear sets left. The last company - US Gear- closed 3-4 years ago. They made the gears for Toms as well as selling direct. All the new gears sold today are imported. I still have stock of NOS US Gear but won't sell them and if I do they would be $650 easy. You have Yukon, Motive, Richmond and reboxed gear sets sold today- all imported.

Corey_68

Yep that is my plan.... appreciate the information.