I have a 68 cutlass type O rear end with axles. This has highway gears roughly 2.56 or so. It is an open rear (not posi). It is complete backing plate to backing plate. No brakes. Take it all or just take the shafts for $50. Pick-up only
I don't know what the spline count is but I can tell you the car was originally delivered with a 6 cylinder motor and 2 speed auto.

 

28 spline shafts.

 

Ttt

 

that should be a 12-bolt with 28-spline shafts.