why wont it work on an automatic? what would the transmission have to do with the radiator? lol

automatics are cooled through the radiator. Take a look at your automatic radiator and you'll notice two little extra ports at the bottom that connect to your transmission. Many aftermarket radiators lack these ports. I suppose you could of course run a separate cooler though instead.

You could always get an external trans cooler if you want a performance aluminum radiator that is meant for manuals.