Ok, go under your car, drain the fluid, NOT HARD. Let it drain well. Meanwhile go have a beer. Come back to car, put plug back on. Look at fluid. Just to be safe, go with some new synthetic fluid. As said, If fluid is not red, get some new stuff. Brown means tranny is overheating.
The lines have directional arrow. You want to disconnect the line that feeds the fluid back to trans. go under the car, and disconnect it from the radiator. Some fluid will probably com out, but not much. Have a paper towel or rag on hand to take care of that. Reach in from the top of the engine and disconnect the same line from transmission. Use pliers. Remove grill to gain access to front of AC core. Find a nice cozy spot for the cooler. See if you have enough lince to get the job done. Mount the cooler using supplied hardware.Connect lines. Fluid will come from tranny, go thru radiator, then out of radiator into cooler then back to tranny. Make sure lines are not in the way of any moving parts or in a location where they can easily be damanged. Make sure clamps are tight. Get a tranny funnel and go ahead and put 4 quarts in. Make sure drain bolt is tight before you do this. Start car and let it iddle as you put in the rest of the fluid. You will need a little more fluid because of the core. Thats it. After fluid is at normal level and car is warm, check for leaks.
DONE. Go enjoy your tranny for the rest of it's life, hopefuly a little longer now with colder fluid.