I drive out on the beach sometimes and I've found that unless I take it really easy the transmission fluid gets hot and I can smell it. My 02 FX4 has the tow package with the trans cooler. I suppose I'd have to add a large trans cooler with its own additional fan to prevent the fluid from overheating if I got aggressive at all on the sand?

What do you guys use to keep the trans cool off-roading?

 

I don't drive in the sand but I tow a travel trailer and I can tell you from experience that the factory trans coolers in our trucks are small and mounted low behind the passenger side front bumper so they get limited air flow. Get one from an F250 SD and throw away the one that came with your truck. The SD coolers are about 2 or 3 times bigger and mount top center of your rad where it actually can get some air. Mine works well. Try that first and add a trans temp gauge so you can see exactly how hot it is getting. If you need a fan you can always add that later.

 

Make that a 2003-2007 Superduty with the 6.0L engine. Some of the Superdutys also had tiny coolers. This one is BIG.