I have a 2001 F350 Dually DumpBody, 7.3l Auto 4x4. Since I bought the truck I have noticed that when it is wet or I stop on leaves and such the front end locks up and the truck skids to a stop. The brakes have been done several times and all the joints/tie rods are good. No lights are on and the fluids are normal. It has all around disc brakes but it does have a relatively hard pedal. Any ideas? Thanks!