under drive pullies

It's my first post! I have a 2000 mustang gt with the 4.6 2v which has a horrible rod knock. I am swapping in a low mileage 2007 4.6 from a Lincoln town car. I have all that I need, but I have found some interesting parts in the mustang which I am unfamiliar with. I am hoping one of you experts...

In the box of stuff that came with my red 91 5.0, (with a 130 amp alternator, AC, titanium and red interior and tinted windows), found a NEW set of (well made steel) BBK under drive pulleys. I have never had cooling issues. The car is apart far enough that putting them in would be no big deal...