Had mine for the 39 built by PRC. I couldnt find a generic replacement everything was to wide and to short. It was expensive, about $450 but that included a built in tranny cooler and the billit cap. They build them to your specs and send you a cad drawing for approval prior to build. You can place the water outlets wherever you want. They are not that speedy though, especially during the cruising months. But the radiator is top notch.

Heres pics of mine
http://hotrodders.com/gallery/data/500/medium/IMGP0099.JPG

http://hotrodders.com/gallery/data/500/medium/IMGP0101.JPG

Heres the link to PRC
http://www.streetrodstuff.com/

1939 GMC Resto-Rod