ECP advertises 1" tubes and they have them, others don't. ECP is the real deal. I have one in an A body with a 511 with hard block within 3" of the deck, mechanical fan and pump. Runs 195* most of the time. 206* highest in 90* 80% humidity. Very nice quality radiator that keeps thing cool. My coolant capacity is only 2gallons and this thing cools. You must have a shroud as well for it to work this good. Very happy.