I'm assuming the '57 was originally a V8 truck. You can mount another radiator support in the six cylinder position, which is about 5 inches forward of the V8 location. You'll have to cut the fender mounts off the v8 support and leave them in place.
I did this on my '56 and installed an electric fan. I used a radiator support from a 2-ton by the way. Whooda thought they were the same?
