what wrench sez - the 56 would have had a 7#, but the earlier trucks used 4# and your rad should take it - also, running the engine warmer is better than too cool, go 180, shouldn't be a problem
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
