If you said "rear" trunion, grind down or remove the head on the other side, put a small punch
mark in the center, use a drill to counter-sink some material out of the center, not much, get
a hard pin punch and slightly heat the area of the trunion nearest the hole, in the center, for no more than 30 seconds, you have one shot. As the outside heats up, it expands. Heat up the
whole area, then give the rivet a whack with the pin punch. If you leave any material on the
head of the rivet, it could mushroom and bind up, the reason for the small counter-sink. Make
sure the pin punch is less than the rivet diameter also. Once the entire thing gets warm, start
over later. Get it when the outside is warmer than the rivet. Use cobalt drills next time, a cheap
drill will really mess the whole deal up! A drill that small needs to be the best. Good luck.