For the GXP the Wbody STB won't work for the fronts without modification.. You have to cut and reweld it a bit so it can clear the alternator. http://www.drcustomparts.com/STBBars.htm
Ok..so the website (BMR) says that it will fit the W body but arent specific on model. But I do see what you are talking about. I will have to check out the other company.