Sorry guys but I got to disagree on the internal radiator transmission cooler vs after market external tranny cooler.
Most air/air coolers only drop temp around about 20 degrees, where a typical rad cooler will drop the fluid temp around 40+ degrees.
Theres a reason they came that way from the factory.
You can get added cooling by using the OEM radiator tranny cooler in conjunction with a air tranny cooler, internal first, then external cooler, not vise versa.
Do the math.
If the tranny temp is 170, and your just using a external cooler, the fluid temp is only cooled down to 150, run it thru a radiator cooler, the fluid is now 120.
Most all radiator transmission coolers are located in the coolest part of a rad, on the return, even if the engine temp is 180 (engine) the rad is not, the function of the rad is to 'cool the fluid, by the time the coolant has circulated thru the rad is has cooled down significantly, usually over 50 to 60 degrees, so that 180 water/coolant is now 120/130 degrees.
The rad trans cooler also acts as a fluid warmer - helping the tranny get up to normal operating range quicker, usually around 160 to 180 degrees.
Beware of most small aftermarket coolers - they are usually quite restrictive and can impead flow.
If you are going that route, buy a nmae brand quality cooler and get the biggest one you can fit in front of the rad with plenty of clean air flow.
>my 2 cents - Cp[/b]