i have never done it but i watched alot of pullin and the thing i see that works best with 4x4 trucks is try to match your tire speed to the sled travel speed.
dont overpower the track on start.
if you start out gung ho you dig up more dirt and add that to the front of the sled, not to mention your digging a hole you have to crawl out of to get a new bite.
once the sled starts to move and you get rollin all bets are off and you gotta get as much ground speed as you can.
the question that comes to my mind is do you wanna select shift and keep it in 2nd gear or 3rd gear, i would think if you let the trans decide when to shift between the traction control and the torque converter slipping you might loose to much momentum
i havent drug any trees with this truck yet so i dont know how it really handles dragging dead loads to be much help
when i see others pull good i cant tell if their was a gear change, it seems like they keep the same gear all the way through