Please excuse me if this is a "Gomer Question" but why couldn't I leave the tire on the ground and put a floor jack underneath the rear spring? Then just put a little tension on the rear spring with the jack and then loosen the U-bolts? Then ease off of the tension on the spring and remove the lowering blocks? Then use the floor jack to raise the spring up high enuff to get the shortened U-bolts installed and the nuts started? Like I said, this could be a real dumb question but I had to ask.