Replacing the H2 air suspension with coil springs:
This is actually a really straightforward project and should only take an hour or so. This eliminates the sagging in the rear end when the air system leaks, because, well, there is no more air to leak! The parts can be had from gmpartsdirect.com:
Left coil: 25956182
Right coil: 25956183
Spacers (x4): 15713853
Step 1: Remove the rear wheels (will make your life easier) and get the H2 up in the air. Then support the rear end. You?re going to disconnect the rear end and axle from the suspension so without support it will fall to the floor!