An adjustable trailer hitch and king pin assembly that may be moved longitudinally to adjust the position and weight distribution of a trailer relative to a truck. The disclosed assembly may allow a trailer to be utilized with various different sized and configured trucks while maximizing the cargo carrying capability and efficiency thereof. In one example, an adjustable trailer hitch is provided having a slidable king pin assembly that may be adjusted forwards or backwards to move the king pin to the desired location relative to the truck and trailer. In another example, a removable king pin may be provided that may be removed and moved to a different location according to the weight and desired weight distribution of a truck and trailer combination.