I replaced 72 rivets on my swb 4x4 and the best way i found is this: Grind a flat on the head of the rivet. Center punch in the center. Drill with a 3/16 or 1/8 drill bit, about 1/4 or so deep. drill with a 7/16 bit till the head spins off. Punch out rivet.
If you dont get your starter hole in the center, the rivet head might not spin off. So keep looking in the 7/16 hole your drilling so that you dont drill through the frame. And then take a chizle and knock the rivet head off. I had two drills so that it went a little faster.

Randy