Need help/ Removal of leaf spring bolts

[super72bb]

I am in the middle of installing some new leaf springs in my 1972 4x4 and have ran into a snag. I had no trouble getting the main bolts which go through the spring eyes and shackles broke loose. When I went to drive the actual bolts out they were so tight I could barely turn them. When I did get them to turn what I found was that the only thing turning is the rubber bushings themselves. The inner metal bushings have seized on to the bolts and even cracking them with a Great "BFH" they don't even budge. I tried drilling them but the grade 8 bolts are so hard that it seems like an impossible task. I dont have much in the way of heating them except with a small propane torch... that also has been a waste of time.

Any suggestions would be so Appreciated!

Curt