If properly done, a welded diff is a good mod for somebody who used their car for either drag racing or drifting, and does not daily drive it.
A properly welded diff will be rock solid.
BTW, i was watching the speed channel last weekend, it was a PINK's special where they were filming drag races at a local track somewhere.
Some moron blew the final drive right out of his chevy blazer while doing a burnout . . .i can only attribute that to shady workmanship like what was done in the main post here lol.