Thanks everyone, I learned a lot. Transmission is stock overdrive, which I plan to not use. Pusher fan, trans temp, and extra gas, got it!
The V10 trans is essentially the same as the diesel trans. Towing in OD is not a problem, especially only 5000 pounds. My V10, with 3.55s pulled my 30 ft enclosed at 80 MPH and never a problem. On long mountain grades you may need to turn the OD off but I wouldn't leave it off. Only turn it off when you need to. Don't lug the engine, slow down and downshift the trans.
