the tensioner pulley is a ford piece (incase you didnt notice the ford emblem on it). youd be better off ordering it from a ford dealership or a ford parts dist. online somewhere. if i remember correctly, there is a part number cast on the pulley.
or you could even go to autozone and they could cross reference the PN and find a replacement pulley. id guess 15-30 bucks.....
vortech parts are about a 300% mark up. i ordered a brass piece i needed, and when i got it, i realized that i could have found it at just about any auto store for about 5 bucks.....they charged me 75!!!!
oh, and by the way, the oil in the intake isnt a good sign. your getting a lot of blow-by. you may be needing a rebuild soon, sorry.
