A CUSTOMER STOPPED HIS TRUCK BEHIND A FRONT END LOADER THAT WAS LOADING TRUCKS FROM A STOCKPILE.THE LOADER BACKED UP APPROX THE LENGTH OF THE LOADER AND HIT THE LEFT SIDE OF THE TRUCK CAB, MOV ING THE TRUCK APPROX 1 FOOT. THE TRUCK DRIVER DID NOT APPEAR TO BE INJURED BUT LATER REQUESTED AN AMBULANCE.