Radiator support

I am in the process of helping my son change his 73 dart from a slant six to a 360. He has purchased a 73 dart parts car that has all of the V-8 parts. It appears that the radiator support has a wider opening on the V-8 car than the one on the slant 6 car. Did dodge make two completely different radiator supports for the same car? How can this be rectified?