Catalyst to Resonator Bracket Problem - Help!
 

I just cut out the old resonator on a 1994 E320 Wagon.

All went well except for the bracket on the drivers side pipe of the catalyst that mounts the resonator. The old bolts were rusted so I simply cut them off mid bolt with a sawzall. When I went to remove the remaining bolt pieces, I found the ends rust welded into the flange.

Since the flange is stuck on the pipe due to a "mounting bell" at the end of the pipe, I cannot get it off to work it on a bench. I have tried beating on it, wrenching and anything else I could think of and they are fused in there.

Any suggestions on how to get these free so I can tame this beast?