I swapped the springs in my Suburban in about 15 minutes.
I spent over an hour trying to get the spring bolt out of a truck in a junk yard... it was rusted INTO the trailing arm, and wouldn't budge. Strangers felt so bad for me THEY took turns swinging the hammer!
Front springs are dangerous because they're captured, and one of the sides won't move (the top of the pocket) and it wants to force the lower control arm down, and are always under tension.
Rear springs aren't captured: when you put jack stands under the frame rails and the rear tires are off the ground, the coil springs are being stretched--there's no stored energy there.
Jack the truck up and put jack stands under the rails.
With the jack under the axle housing, apply enough lift to the housing so that the springs aren't stretching any more. Put just a liiiiiitle upward pressure on them, so that they are very, very slightly compressed, and remove the bolts. The upward pressure will keep the bolt threads from supporting the rear end housing as you remove them--it just makes taking the bolts out easier.
once the bolts are out, slowly lower the rear end housing--it'll just lower from the springs... no muss, no fuss.
-Brad
