Narrowing truck 8 3/4

Please burn that POS chart. That fricken chart has destroyed more rear axles of people wanting A-body length rears than anything on the planet.

It's 52 5/8" to the flanges the backing plate bolt up, in other words the housing ONLY. If you want it to be exactly the same total width at 57 1/8" using bbp axles/drums, it needs to be a bit shorter.