Replaced the rusty top section of all eight body mounts on my ECSB 94 Chevy with some heavy steel plate. All it took was two 2" hole saws, a roll and a half of MIG wire and MANY hours work cutting, fitting and bending. Bending was the hard part with that heavy plate but it had to be done because the frame mounts are not 100% flat as seen in the second photo below.
And lots of rust paint after the grinding and welding....
Took the front clip off and jacked the cab off the frame about 6" one side at a time to make the welding easier
Also put on new front fenders, inner fenders, radiator support, Y-pipe and gaskets, catalytic convertor and a couple of patches on the cab floor with 18 gauge steel(easier to weld) All in all it took 120 hours from May 6 to June 5 and was all done home in my gravel driveway in between the rain(and snow) days.