Can I build a diff myself, and anybody used this tool?

Thanks for the info everyone. I've read about getting another bearing just for that purpose, Coronet. MoparMitch, I figured if that tool will do the trick, probably not a big deal to do myself. But the actual pinion depth finders at $100 and up, I'd probably just have someone else do it. Assuming it will take me several hours to do for my first time. These sub-projects on the car are what kills me!