On a 2004 Silverado C1500 WT, I'm considering swapping out the Dash wiring harness with another truck. WT models don't have the same wiring features as base models, steering wheel controls, electronic mirrors, etc. In 2004 and up, GM deleted courtesy lights. I've heard that GM changed wiring between 2002 and 2003. However, the wiring harness (GM Part # 15196623) on some sites is listed as fitting 1999-2007 Silverado and Sierra Trucks. I can likely pick up a harness for $35 at a junk yard. So I'm thinking a 1999-2002 Sierra/Silverado may work...and a 2003 should work. Any thoughts/comments/corrections/tips/gotcha's on the above information? Will a harness with Onstar/power windows/etc. still work? Will the heater core need to be removed? Anyone have any information on which harness will fit mine for sure? If feasible, is there anything you would recommend replacing during this massive swap?