Just saw this thread. One of my biggest gripes with my GMT800 Duramax is the waxed frame getting eaten by diesel (,,,its inevitable diesel makes it to the chassis via fuel filter changes, leaks, etc).
I am forevever inspecting and recoating the frame, and am dissapointed to hear the 1500's are still being waxed. Especially since it appears on the new Colorado/Canyon twins they are actually painting the frames (good news for those waiting on the babyDmax engine).