I have a 2004 SL and purchased the SAT (XM) radio locally - I have taken the car apart but cannot find the prewired harness? Is it just laying there? Could I possibley have an early 2004 that was not prewired? Has anybody out there done a 2004? I see a ton on putting the sat in a 2003 but not much on the process for a 2004 - thanks in advance for your help.