Removing coil spring rear end.....
 

whats the the best way?(70 1/2 ton)..thanks for any help.

Pretty simple mechanically, but a real knuckle-buster. First, drench the panhard bar nuts and bolts, and the U-bolts that go through the trailing arms (and hold the axle to the trailing arms via the perches) with as much Kroil, or other penetrating fluid as possible. The trailing arms are going to fill up with rust and other gunk and basically weld the U-bolts in place. I'd recomend either buying or renting a 3/4 drive socket set and breaker bar. This saved me tons of work.

Put some jackstands under the axle tube after removing the rear shocks, and jack it up where there's slight compression on the rear springs (not a whole lot!). Remove the panhard bar.

Once the axle is essentially floating by the coil springs remove the giant nuts off of the U-bolts. This'll take a while, so don't give up. Use the propane torch to loosen it up, and once it cools down douse it with more penetrating oil. Be careful not to start a fire.

Once they're off then BANG the U-bolt up far enough to get some space between the saddles on the axle tube and the trailing arm (enough to get a saw blade in + some extra space so you don't scar up the trailing arm or the saddles). THAT'S RIGHT! You're going to cut them. They won't come out straight (unless they've been replaced before), and you'll end up mushrooming the ends trying to pound them out, so just resign to cutting them.

Once they're cut loose (many moons and saw blades later) disconnect the brake lines (you have it drained, right?) and the axle will come right out.

NOTE: When putting the axle back in remember to connect the panhard bar FIRST before installing the new U-bolts...

Have fun.

Thanks, Cobalt. Where do you recommend getting new u bolts?

Generally there'll be a big truck suspension shop around you. They'll make them for you. You can't get them at a parts store. I got mine from LMC, and they weren't bad, but I had to open them with a spreader (they were bent over too much).