Just a few general questions- My 69' Coupe has a 3.70 axle (according to the code).

Were ALL 3.70 gears posi or did they actually have 3.70 open ends in 69?
At 60 MPH, I rev at 2750-2800 RPM in 4th with P225/60R15 tires. Does this sounds about right for a 3.70 gear?
I was expecting it to rev somewhat higher.
Thanks!
Elm.

Posi-trac was a $46.35 option with all axle ratios in '69, and the vast majority of Vettes were so equipped (36,965 out of 38,762 Corvettes total).

Your rpms sound pretty normal to me. My '69 has a 4.11 rear and at 60 mph I'm turning somewhat over 3000 rpms with P215/70R-15 tires.

at 3.36 i run 3000 @ 72mph

http://www.5speedtransmission.com/gear_calculator.html

this link says you should run 2915 RPM @60 mph

a 3.55 has 2797RPM @ 60 mph

could a PO have swapped it ?

question for you though..

why the small tires ??

|UPDATED|6/24/2004 2:17:49 PM (AZT)|/UPDATED|

Since the car is 35 years old, the possibility of the gears being swapped at some point is very likely.
The carrier itself is for the 3.70 but until I either open the pumpkin or start counting turns on the driveshaft, I won't know for sure.
If it's anything below a 3.70 (numerically), I would have to seriously consider either swapping the gear or going to an M-20. My off the line kick, even with the ZZ3 motor, is somewhat disappointing.
The P225/60R15's are plenty big for my use. If I can't turn these puppies over now, why go any bigger?!