Rear Axle Swap Problems

[Andrew68c10]

I'm swapping out my rear axle. I have all the parts stripped off, and the u-bolts are undone, but the trailing arms won't come loose, and the u-bolts won't come out. I even had me and the kids jumping up and down in the bed of the truck to try and get the trailing arms loose, but they don't budge. Anyone had this problem before? I tried various hammers and I ruined a good crowbar already.