Someone recently sold a tropical fan on ebay stated to be for an TR3. Just last night I was looking at an old repair manual that had information on the 4 and 6 cylinder engines in it. It had a picture of the GT6 fan and it sure looked like the one that sold on ebay. 6 blades and the mounting holes looked to be the same. Are these fans interchangeable? I'm I correct in thinking that the Tropical fan was an option for the TR3?