I’m running 33’s and had a 4 bolt 31/4 turn Saginaw that was too fast, changed to btb Saginaw box that is supposed to be valved different for the fj40 application but saw no difference.
I bought a rebuilt one from mark and it’s awesome, with new tre’s and marks rebuild almost no play. Also keeps my factory wiring for horn and turn signals the same. Piece of cake