From all I learned during my swap, There is no t-valve for the cooler. The cooler in the bottom of the radiator is actually as much (if not more) of a warmer during cold weather as it is a cooler during hot weather. I don't drive mine much in cold weather, so I did not run through the radiator.
As for the cooler itself-
Don's truck probably saw (prior to 4.3 conversion) a harder life than most, due to long road trips towing a big travel trailer. He replaced his stock one with a cooler with an aux fan. He used one out of a Ford pickup, but your's would be the same setup.
I used the factory one, but it's out of a V6 truck. There is a pretty substantial size difference over the 4cyl cooler, and I've not had a problem

BTW- Glad to see you back at it! <img src="/forums/images/graemlins/kewl.gif" alt="" />

-Dave D
Reservoir of Useless Knowledge

"But... If I kill all the golfers, they'll lock me up, and throw away the key..."
-Bill Murray

'84&change Monty MPI Turbo, choptop, f&r lsd, swapped in AT- All the goodies!