Thanks Bill, this sounds like progress. I have HD and doing OE to OE replacment. In general, I want to measure existing, and then match new to that measurement. Simple, make sense. But I'm dense, so...

1st, do you recommend measuring on-car, or off w/ diff vertical?
2nd, what am I measuring and matching? eg, outside face of thr brg (715) to what? or other?

BTW, I'm learning stuff