There are two types of cores, crossflow and downflow. Downflow is standard in trucks of this age. The coolant enters the top tank and drops down through the core and exits the bottom tank. In a crossflow core, the coolant enters the top of one side, flows across the length of the core and exits the bottom of the opposite side. Some crossflow cores make several passes across byway of blocks in the side tanks. Think of a "S" pattern, the coolant gets to cross the air flow three times instead of just once.
I went with a overseas aluminum radiator to save money. Coming from a drag racing background I seen first hand how well the aluminum cooled. Mine has 2 rows of 1" tubes. I had to reroute the lower hose since the outlet was pointed a different direction, but in the end, the system held 1 gallon more of coolant the old stock radiator did. I suspect half was from the core and half from the new longer hose. Since the swap, the temp runs dead on the thermostat temp. On the plus side, its now a full pressure system that came with a 22 psi cap.
Joe
