I have welded them up with MIGs too. ALways have worked just fine. They are fast so the heat stays localized. I have even welded shock mounts on my 1 ton axle and they are still holding on fine with a MIG as well. (Actually flux core wire welder)

\'59 Chevy 1-ton
'72 c-10 (in progress)
The Great Rust(less) Mountain
\'47 Jeep cj2a