I have never looked into adding a cooler to my manual transmission mainly because I'd have the minor hassel of having to add a pump. Auto transmissions, generally, already come with a crude cooler from the factory. Again, I have never looked into how effective they are. It will just look like a metal loop. If you trace it back to the transmission you just remove the factory one and replace it with a larger, finned cooler and run the hoses to the front of the car. But make sure it isn't one of those 'tube and fin' (aka snake, s) coolers as they do nothing. 'Plate and fin' is where the results are.