Trouble With Magnaflow Cat. Converter Install

I have been outside all afternoon trying to think of a way to get this rusty piece of shit stock converter off of my truck so I can install the new one. My current one has been rattling for about 2 years. My problem is that the bolts are rusted and I can get to 3 of the four bolts with a grinder, but the back, driver's side bolt is impossible to reach with a grinder. PB blaster hasn't worked so far and now the bolt is rounded off. My best bet is a saws-all I think, but I do not own one. I'm stumped and I am looking for suggestions.

 

I bought the weld in one so I just hacked it off

 

I'm regretting the fact that I didn't do the same. I have a guy that works at a shop around town that offered to cut it and weld it for $40. I would rather bolt this one on so I can take it off easier later, but I guess it has the same rust potential that the stock cat did.

 

My magnaflow cat was stainless body, and I installed it with stainless bolts because of the rusted bolt problem. I had a mechanic grind the old bolts out, they were all accessible on my truck.

 

Torch! Extremely useful tool