narrowing an 8&3/4" rear

It's easy but you absolutely have to have a narrowing jig. No iff's, and's. or buts! Pretty close isn't even in the ballpark. It has to be absolutely straight. Not .020" off end to end. If you don't have a narrowing jig don't even try it. Also, the jig must be in place when welded and left until the housing cools or it'll warp.