checking rear end housing straightness

Rapid Robert said
excellent info. Actually I have an 8&3/4 and a 5:57 pumpkin (probably deeper than I need) with welded spiders but the dr diff axles will not go in all the way. still haven't figured out what is wrong there.

I have a gaging tool for an 8-3/4. Consists of 2 bushings to be clamped into bearing saddles of the carrier along with tubing extending to both ends of the housing. From there use calipers to figure centeredness of the axles relative to housing ends. You can make this stuff easily using a local machine shop.