The hot line is a AN-8 female, the water heat exchange rear (toward the cab) is an AN-8 male.
Everyone tries to get the shortest line. You will find that the alignment of the water heat exchanger with the transmission hot line is NOT very well aligned. The line sidesteps about 1" - 1 1/2".
My point is you could put a complete loop of a line in and not have the sidestep tension. Enough AN-8 line to hook to the water heat exchanger, do a complete loop, then hook to the transmission line. Make sure the line does not kink in any way since this line is the cooling life line of the transmission.
There is also a check valve in the water heat exchanger rear port. The short rubber line you get from DC also has a check valve in it. You do not want two check valves. IF you want one check valve then pick which one.
I took my check valves completely out. The DTT line does not have a check valve in it. My theory was less restriction in the line without a check valve. Without checkvalves you DO HAVE TO choose NETURAL (OEM transmission) for 30 seconds before a gear because the fluid might have drained back down into the pan. Depends on who will be driving the truck and how carefull they are if you want to consider that or not.
Bob Weis