Dr. Diff BBP axles with 11 x 2.5 Drums

if the axles are for redrilling the "stock" small bolt pattern drums then the center register should be the same smaller size.
if not its likely set up for the large bolt pattern drums AND backing plates and has the larger center register.
any large bolt pattern rear brake COMPLETE ASSEMBLIES from 65 thru at least 89 (has to be rear wheel drive) will fit.
My axles, from the good Dr, are large bolt pattern for standard large bolt brakes. I have a set of 11" brakes from a 74 Satellite on the A body 8.75.