I'll leave it to others to name the many different companies who make after market radiators. I will point out a problem that can occur with built in condensors or any condensor for that matter. The condensor is the A/C's way of removing heat from your system so it must work in concert with the rest of your cooling system. Too small a condensor and it won't be able able to waste the heat load. I believe the general rule is to get as much condensor as you can stand. I also believe the most common setup you see is a condensor mounted in front of the radiator to increase the condensor size. All in all you just might ask the guys you buy your cooling system from for their recommendation. A system that doesn't cool for whatever reason doesn't help them sell more units.

Six volt guy living in a twelve volt world