What rear is this?

The early BBP 7 1/4 (don't know years) did not use "C" clip axles (had the bolt on bearing retainer). Also the main axle tube is 2 1/2 inch, but the bearing end was enlarged for the bigger bearing. I think (but not sure) "M" bodies used both the 8 1/4, and 7 1/4 rears. I think these 7 1/4 might have used "C" clips.