I too have had a welded diff lock up on me, someone from St Pete gave it to me and on my way home from OSW it started making sweet noises, the next day it locked ON the way to the auto parts store to get gear oil and RTV to put in the new one Ranlet welded up. (Broke Driveshaft, Transmission AND of course the gay-ass diff.) When it locked up I was on a 2 lane road and both wheels LOCKED and started fish tail as if I had Zangief kicked the clutch pedal to the floor and full locked left..if I didn't know how to respond to that it would totally go back to what Tim said: Yeah you'll probably wreck die

OH, and OP if you decide to go the welded route, MAKE Sure you get a reputable welder to do this job. I remember there was a "tech" thread on SFL a few months back talking about some idiot JB welding his diff..

You should have basic car control skills if you are going to put a welded in.