When I stop, I hear a thud in the back of the truck and I feel pressure pushing the truck forward. I had the differential worked on, and this did not stop the problem, however, the rear end fell out on the train tracks, and when it was taken in to be serviced for this problem, they replaced the bearings and other things and tightened the back end, so this did solve the problem for about a month or two, but I began to feel the backend loosening up again. Now I am right back to having the same problem. When I am at stoplights, I can take my foot off of the brake, and the truck will not move unless I press on the gas pedal. It feels sort of like it is dragging when I have to take off from a stop sign or stoplight. I have taken it back in and explained the problem again, but the mechanics cannot seem to find anything wrong with the back end, but I know there is definitely a problem.