huh i put the same tails on my 99 gmc, i just modified the socket holder on the tails them selves with a dremmel and under 15 min i had them in with whatever was stock in the back, since i bought them from a guy for 20 bucks and they didnt come with any harness. Everything works fine as far as i have seen, im sure they have switched a lot since then. They bolted right up and every thing lights up according, brake lights on top, blinkers underneath, and back up lights. Heres a couple pics, not the best since im living where i go to school for the summer...