OK, so here is the question:

Is the air in the bed just in front of the tailgate, High pressure of Low pressure?

I have a NASCAR truck style wing on the tailgate and vents in the bed above the tank to vent the transmission cooler. Should the transmission cooler be pushing air up into the space (Low Pressure) or pulling air down onto the cooler (High Pressure)?

Short of putting pieces of yarn (Ford Vs. Ferrari style) I thought one of you brilliant minds out there would have a good answer.

Back.jpg
Bed vent.jpg
This is not my, but it has the same NASCAR wing.
Blue Truck.png

I don't want to fight the air pressure that is already there.