I have noticed that my transmission shifts much smoother and precisely when it has a load on it. Pulling my trailer or hauling anything over 1500 lbs, is when it is noticably better. I am the second owner of this truck, so is there anything aftermarket in my transmission that I don't know about that would cause this? I know there are some 47re experts out there, so shed some light on this for me. Thanks

 

More weight = more throttle. This will increase line preasure and change the shifting. The line preasure changes when you increase throttle, as you increase throttle the throttle valve in the valve body moves to increase the preasure. A shift kit will change the feel when you are empty.