The usual way to connect an auxiliary cooler is to put it downstream of the radiator cooler. Otherwise, the fluid cooled by the auxiliary is re-heated when it gets to the radiator. Disconnect one line at the radiator, start the engine momentarily, and see which way the fluid flows. Connect the add-on cooler so the fluid comes out of the radiator, goes through the auxiliary unit, and then route it back to the transmission.
With a couple of "T" fittings and a cutoff valve, you can bypass the extra cooler for winter operation when it might over-cool the fluid.
Jerry
