Tough nuts??

[novaX522]

Trying to break loose the U bolt nuts that hold the rear end to the trailing arms. I’ve been basting them with PB Blaster several times over the last week. The threads look pretty decent, but I can’t get it to budge. I bent a 1/2” drive breaker bar. Any pointers?
I can have my friend bring his torch to heat them up, but at that point I should probably replace the u bolts.
Sounds like I answered my own question. I’ll cut them off and and get new ones. What is the torque supposed to be?