[nnorton44]

The Trailblazer/Envoy series vehicles use aluminum calipers front and rear. The fronts have double pistons, the rears have single pistons--at least the ones I've looked at. Ravalli has "Cop Car" brakes which may be different.

Then in 06+ the calipers are cast iron (4.2, EXT, 5.3, SS)