The addition of a transmission cooler is always a good thing and I have wanted to do it but just now got around to it. Most cooler and automobile manufacturers information we have seen documented have you installing the cooler inline with the factory radiator cooler for maximum cooling efficiency.
One such rumor that says to bypass the radiator unit entirely. Unless the manufacturers with many of hours testing different installations is way wrong this is a bad idea. A main reason for this is that the radiator unit acts as a temperature stabilzer [ winter especially! ] and any extra heat is taken out by both the internal liquid and external air coolers.
Mine is inline on the return side as it should be. The cooler is actually a 6 row plate style unit from the Mopar parts bin. I have seen it installed on both cars and trucks. And I had a few already here in the shop. It is great unit because it has threaded SAE flare style fittings on it so it plumbs up easily using standard SAE tubing.
I mounted it in front of the radiator on the left side with some flat stock bars. The plumbing goes around and down to the original trans lines at the bottom of the radiator. Small sections of fuel line were split and wrapped around the tubing to act as chafe guards where they pass through the core support. I fabed a small L shaped bracket to support these lines where they loop back toward the radiator and fastened it to the tub. A quick cut, plumb and some clamps using trans cooler line and the hookup surgery is done.