[electricjohn]

4200 lbs is not alot of weight. I've towed 5000 lbs in both D and 4 with most travel at about 70 -75 mph. The only difference I noticed was a very slight mileage increase when towing in 4th. At that speed the torque converter never unlocks in either gear, so trans. temps always stayed at normal. If I'm towing in 4th, I will upshift to 5th(D) when speeds get upto and above 80mph which is not uncommon on the N.Y. State Thruway. If I stay in 4th, I'm tach-ing like 2800 rpm. That to me seems unnessessarily high. Another thing to consider is the fact that a boat does not have alot of frontage like a box or travel trailer would, making it an easy 4200 lbs tow.