Front Springs
Standard Spring - Before
Heavy Duty Springs 
The springs here on the right are the really heavy duty springs, may not look like it is much bigger but the diam of the HD springs is larger. They are solid riding springs. I collaped 3 sets of the standard stock spring with in a year. One set was within two weeks. I know I am not that ruff on my truck, but.... With my new heavy duty set of springs I am able to maintain the 16 inch clearance on the front end, unlike the stardard ones on the left that also allowed the ride side tire to hit the air filter that in turn hit the hood and cracked it a little..
Front @ 16.75"
Rear @ 19.25"
Front now with the clearance of 16.75 inches, before it was just at 15 inches. The rear clearance is at 19.25 inch. The clearance is taken from the cross bars front and rear.

How to take the measurements:

  1. Set tire presure, front 26 PSI, rear 28 PSI.
  2. Position vehicle on hard flat level surface.
  3. Remove all load.
  4. If you have added a winch or aftermarket brushguards, may invalidate warranty replacement of coil springs.
  5. Bounce front and rear of vehicle up/down several times to make sure it is fully settled.
  6. Measure the distance from edge of each lower control arm front crossmember bracket to shop floor.
  7. If distance is less than 16" and/or if the left and right side measurements differ by more than 3/4", then warranty will replace springs, If vehicle is covered by original warranty and has not been modified.
The Above springs are of 94 Hummers.