If you have 1.75" 8 3/4 backing plates and drums you will need A body brake back spacing axles.
As noted above, the drums will need to be redrilled for 5x4.5 and the center index MIGHT need to be made bigger (unless the axles are made with the smaller A body register)
All correct. Moser sells the axles that will work, but if this is a clean sheet of paper build, it is wise to go to the much more common (and available) B-Body axle and brake configuration.
