A guy on my website made the mistake of buying a UDP for his 420a from ebay. They sent him the wrong pulley. Another thing is these UDP's need certain belts. The AF/X Underdrive pulley from Howell Automotive is the way to go and brings the belts also if one were to break they sell the belts on the site as well. Based on other's experience's its one of the best mods to put on a NA 420a. A lot better then some throttle body spacer IMO.

There's a lot of things you can get off ebay... the UDP for our cars (420a powered) is not one of them.