I broke off 3 of the 4 upper bolts when I put my Sensa-Tracs on. A little time with a large hammer and a metal rod and I broke the weld-nuts out. Fished some bolts in with some wire and I'm all good now. It was a pain in the ass but not impossible. It was a full day of work, but mostly because mine's a 2001 and by then they were fully welding the nuts on... not just tack welding. That took the majority of the time and effort. Soak them repeatedly with PB beforehand and you might get lucky. If you're not feeling like a shoulder workout, it's probably worth trolling a shop into doing it if you can get it done cheaply.
Check their fuckin' work though.
Also, there is a possibility of breaking the bolts for the leafs, so I bought 2 OEM leaf spring bolts just in case that would be included (assuming they are still in the U-bolt box, and I think they are). I tend to over-plan.