2500 4x4 turbo diesel with a ATK ?? aftermarket trans.
We took a thick rubber drawer liner for a tool box used washers and rivets to secure it to the inside lip of the lower spoiler . Its cut the width of the frame. Then you use washers and plastic rivets to secure it to the bottom of the fan shroud. That way if you need to remove the shroud you can just use a razor knife to cut the heads off the plastic rivets.
then use a hole saw to drill a few air vents. this not only allows air to rush in . It seals off that big gap and directs more air pulled in by the fan to come thru all 4 coolers.
We also sealed the top the same way now the fan is pulling air straight thru and not from the top or bottom.
Just did this last night and it helped a lot. We will find out tomorrow going to pick up 2000 pounds of corn.
No I didn't drill the holes........While I was looking for a tape measure the owner (my boss) started eyeballin' it.;(