Both sides completed. From start to finish (not encluding the paint job; obviously) the tail light upgrade took less than an hour. It took me about ten minutes to remove all the original light parts and another ten minutes or so to cut the holes. After the paint job it took about ten minutes per side to install the new lenses. I never could understand why other GMC folks hack up the lens itself. This way, I was able to use late model right-angle bulb sockets which leave more room behind the tail light assembly for other things. Also, the new bulb sockets are more reliable than the original stuff.