I always thought they dropped the number of tubes so that they could increase the size of the tubes themselves to add more coolant flow and have more area in between them to get added air flow through the radiator to the larger tubes. I could be way off but I always thought that was the other reason for buying an aftermarket radiator aside from the aluminum helping with heat dissipation.
The stock OE rad I removed was a 1 row, 1" thick core with 62 coolant tubes. The aftermarket OE style replacement rad I installed is a 1 row 1" thick core with 67 coolant tubes. Since each tube is the same size, having more tubes (67 vs 62) means more coolant in and flowing thru the core. More metal surface area means more heat being extracted from the coolant. Modern rad design over the past 20+ years has gone to less number of rows but much wider tubes, ie. 1 row of 1" wide tubes with a higher fin/inch count (modern) vs 2 rows of 1/2" wide tubes and less fin/inch count (old school).
It would be interesting to know more about that Ron Davis rad. We already know it has less tubes but how wide are the tubes, how thick is the core, how many rows and what is the fins/inch count??????? Basically all we do know is, it has less rows, it's expensive, and it's pretty. Devil's in the details, regarding efficiency.
