Quick question ref: stuck bolts in trailing arms

[Jackson's Dad 64 C10]

Our 64 is down to a bare frame right now. My son and I decided to keep the stock trailing arms, which are in good shape. We are doing some upgrades from No Limit. The factory coil springs are stuck on the trailing arms, and I cannot get the bolts to let go. I can't find a good pic of the stock trailing arms to answer this question. Is there a welded nut or any other sort of threaded fastener on the spring side of the trailing arm? Or is it pretty much just a bolt through the arm, with a spring seat (or whatever it is called) that has the welded/threaded part? I'm trying to decide if I can get a cut off wheel between the top of the trailing arm and the spring. Cut the bolt, spring falls off, bolt falls out. Failing that, I'll go back to penetrating oil, heat, and cussing. My impact gun won't budge the thing, and my breaker bar/cheater bar combo didn't do anything either. Thanks!