Chev Blitz Replacement Radiators.....
 

I have found a company that can supply the exact new replacement radiator for the Chev blitz, ( and Fords ). They are made in the US as well.

http://www.usradiator.com/chevrolet-...-radiator.html

Although they don't deal direct you should be able to find a dealer that may be able to order one in for you.

Picture of Chevy version below.....