which transmission cooler lines do i need?

hey guys

im getting parts together to swap a 360/727 into my 71 s6/904 duster and im wondering which transmission cooler lines I need ?
the right stuff has 2 sets listed, the 6901 http://www.getdiscbrakes.com/ytc6901
and the 7001 http://www.getdiscbrakes.com/ytc7001 (which has a loop near the radiator)
I asked them the question but they couldn't tell me what the loop was for and if I need the ones with or without it

anybody have any experience?