10 inch rear drum brakes

The backing plate offset from SBP to BBP brakes is different, because the axle flange offset is different between SBP and BBP axles.

View attachment 1716220200

So if you’re switching from SBP brakes to BBP brakes, you also need to be switching from SBP axles to BBP axles (and not just a re-drill either)
Thanks for the response and information. Again, just the information I need to know. Keeping me from making mistake.