Well, budget about 1-1/2 hrs to take grille/bumper off and take the bumper apart. Use a huge sheet of cardboard on your work surface, and also a thick blanket. Reason for that is the bumper will want to rotate and move around a lot, and it balances on the chrome and the front painted surface of the lower cover. Scraped up paint and chrome kinda makes this whole exercise pointless, doesnt it?
Got all my brackets off, only lost one mounting bolt (RH outer tube-like bracket to bumper bolt. Darn it) and all four foglight bolts (meh). Paid off years ago to put some anti-sieze on all the main bolts when I had the truck apart for the engine rebuild.
Those blind carriage bolts on both sides and under the center are sure fun to remove, too. Even saved all the speednuts. Crazy.
The GMC lower cover attached to the metal bumper with
17 large double-action pushpins, and 6 metal clips on the sides. Those side clips are attached to the cover on some VERY small, thin outriggers.....and they can break very, very easily. Be careful. Mine had all three on one side broke off already. Will have to epoxy those all back on. Yay.
You pop the center of the pushpins like normal. Then rotate the pushpin body so the slot in the pushpin body matches the slot in the plastic recepticle on the bumper itself. Pinch the end of the pushpin together while prying the pushpin out......17 freaking times.
After the cover is off, then remove the 17 --- yes 17 -- plastic recepticles. You just pinch the sides and pull the plastic piece out. Trust me...it'll all make sense when you see them.