Correct on row identification. The very best aluminum radiators built at Mark 7 machine utilize two rows and they are 1 1/4 each therfore you receive a full 2 1/2 inch of tubes, this would compare to a 5 core copper/ brass unit. Check out the Mark 7's at :
www.mark7machine.com (989) 922-7335. He also builds custom fan shrouds in raw aluminum or highly polished and or anodized in a rainbow of colors just like the custom radiators. There is a HUGE difference in cooling capabilities with those extra 1/4 inches per tube.
Tim john---