10"x 1.75' brake drum BBP???

wrong guys.
10 x 1.75 BBP drums were used on slant six equiped B-bodies like a 67 Belvidere
Drum p/n 2534 173

All four brakes, shoe & lining package
View attachment 1715497617

Rear wheel axle set, shoe & lining package
View attachment 1715497618

But the real question is, what is the offset? Because the BBP axles all have the same flange offset. Which is different than the SBP axle flange offset.

So if the OP has SBP axles that have been converted to BBP and wants to use his SBP backing plates those drums still probably won’t work.