I have a 1970 Cutlass, I think the rear-end is a O axle, The rear-end did not have C-clips only press bearing holding in the axle rods. Can any tell me what other rear-ends I could use that are more common. Chevy ?

 

Any 68-72 A body rear should fit. That includes the Chevy 12 bolt, O type 12 bolt, BOP corporate 8.5 10 bolt, and P type 8.2 10 bolt.

 

And choose axles with coil spring setups from among those.

 

These are A body vehicles:

Chevrolet: Chevelle, Malibu, El Camino, Monte Carlo
Pontiac: Le Mans, Tempest, GTO, Gran Prix
Buick: Gran Sport, Skylark
Oldsmobile: Cutlass, F-85, 442