The 73 up parts will not work unless you add box coupling, center link, idler arm, and idler arm to K member mod', to your list of parts needed.
Not a 2 groove pulley but a second pulley stacked for the added belt.
Please beware the 3 nutsand bolts that attach the steering gear to the K. They should be cleaned, checked, loctite added, etc.. Cracks and breaks in the steering gear mounting is a typical problem ( or nightmare ) in the early a-body K members.
