Axton,you running a 56 235 in an early truck? the problem is typical of the low fan position cause of the low mounted water pump.If ain't radiator paint or phases of the moon,it's the pump location. Get a pump adapter to use a 216 pump,raises the fan about 3-1/2 inches,or go electric fan,or a fan shroud at the least.
The low mounted water pump is driven at slightly less than engine speed,the earlier 216 pump is driven at 1.4 times the crank speed.
