ASD, you want to hook up with your local 4x4 association, and find the guys that mount their rads in the bed of the truck or on the roof. They know what their doing when it comes to cusotm work, and can either fabricate one for you, or direct to to their local hi-pro shop.
another source is the guys that mod thier trucks for rock crawling , they often mount the rads behind the cabs.