monarch

Hi, I'm sort of new here, I've been lurking for quite some time.
I've got a 1990 LS 400. Here's the deal, while i was changing the plugs wires, caps and rotors on it, and I messed up the radiator. It was a mess, covered in dirt and leaves, i tried washing it off, but it wasn't happening. The car has 282,xxx miles on it and it looked like this is the first time the radiator had been off. I finally did get it cleaner, but also leaky. So I considered my options and ordered a new radiator and tranmission cooler, better than takeing it to be "rebuilt". It's not an original radiator, but an aftermarket chevy style one (same radiator fitings, same size, but no trans cooler)
Now here's my question, what about the third tranmission line that goes in at the top of the radiator? The two at the bottom are easy enough.
It's going into a 25,000 lbs trany cooler. so i don't really have to worry about capacity.
Do I just make a T in one of the lower lines?
And if so, which one? to the transmission cooler or away from it?
Thanks,
matt