[undy]

I switched from the Spal fan on mine to Flex-a-lite's 180 Extreme Black Magic.
I comes with a nylon shroud (I modified to fit) and is rated at 3300 cfm. It runs hotter than it did before. I'm a bit dubious of it's 3300 cfm rating.

As far as the at idle rear to front air recirculation issue, that's an easy one to diagnose. With the hood closed pack all gaps from the top, sides and bottom of the radiator with rags to eliminate air migration. Fire it up and see if there's any temp difference.

I think the key is a better shrouded fan. I also think that Lone Star's wiring to the fan is inadequate to handle the "higher amp" fans too. I plan to do some voltage drop readings when I get a chance. If there is a drop I'll run some #8 wire from the battery to the fan motor.

Dave