Just a quick note. I just replaced my resistor pack using the most excellent guide posted here. I do note that the unit installed in my car was white plastic, and does not have a 3M5Z-18591-BA part# stamped on it. I pulled 3 units out of junkers at the Pull-n-Part, from base model contours. Some were white, and one was blue. Tomorrow when I collect my thoughts I will post some pics and open discussion on why this is a really crap design.