Narrowing truck 8 3/4

You need to know some info about the brake rotor hat thickness, backing plate/disc bracket thickness and attachment style.

A std A-body rear is 52 5/8" housing flange to housing flange. 57 1/8" overall where the wheels bolt up.

There is a POS chart floating around that has a 51.40 number and it is BOGUS! Don't cut it to that length, you'll be sorry.