Will this damage anything?

I do have another question. Which hose on the slant 6, "heater hose",
can I install this flush kit on? The "T" fitting?
I have a 5/16 hose, and a 5/8's hose.
I am gonna flush with the upper and lower off,. but since I bought the kit, I might as well install it, so I can do it while its running to, when I hook my rad hoses back up. I didn't know if it mattered on which heater hose to put the "T" fitting on?