C2: G81 w/M22

[Wayne M.]

Anyone know if there is a difference between the posi differential for a factory-equipped M22 car and the standard big-block unit; that is, anything OTHER than the yellow water-resistant cardboard tag #3892548 attached to the filler plug with wire, with the wording [Use axle & transmission D-A SUPERSPORT 90 GEAR LUBE, D-A Lubricants - Indianapolis, Indiana / or its equivalent], as shown in Noland's Vol 2, page 343 ?

Would this variation alone merit the different ECL code for G81 w/M22 ? Would the assembly stamping on the bottom of the carrier case still be FA for a 3.70 ratio, or were there other beefed-up internals ?

[Joe L.]

Re: C2: G81 w/M22

Wayne-----

As far as I know, the only differences between 1965 to 1979 Corvette differential carrier assemblies was the gear ratio (ring and pinion), side yokes, and rear cover.

1965 to 1974 big block carrier assemblies, so-called "heavy duty", differed only with respect to the side yokes. Big blocks, of course, used the forged cap u-joint retention and most small blocks used the u-bolt style attachment. After about 1972, some small blocks also used the forged cap u-bolt retention. In 1977 the rear cover design was changed to accomodate intallation of the 2-1/2" wide leaf spring and 7/16" spring retainer plate bolts.

Otherwise, and as far as I know, there were no internal differences in the differential carrier assembly's components.

1963 and 1964 differentials are also the same, except that the pinion gear shaft splines and the positraction unit(late-64-up) are different than later models . 1963 and most 1964 use a Dana-manufactured positraction unit whereas late 64-up use an Eaton-manufactured unit. They are interchangeable, though, as a unit but not with respect to component parts.


Cranes Corvette