OUR 2001 CHEVY K2500 HD WAS PARKED, W/PARK BRAKE ON, AT THE TOP OF A MNT. PLATEAU WHEN IT ROLLED OFF THE TOP W/A 5 YR OLD BOY IN THE BED OF THE TRUCK, GOING 500 YDS BEFORE COMING TO A STOP. THE TRUCK HAD BEEN SITTING FOR APPROXIMATELY 10 MIN. AT AN IDLE BEFORE IT BEGAN TO MOVE. NO PREVIOUS PROBLEMS WITH THE PARK BRAKE FAILING EVER OCCURRED PRIOR TO THIS. OUR TRUCK WAS TOTALED DUE TO DAMAGE SUSTAINED IN THE ACCIDENT. THE 5 YR OLD BOY REMAINED IN THE BED OF THE TRUCK DURING THE RUNAWAY. HE BROKE HIS JAW IN THREE PLACES AND FRACTURED HIS RIGHT ARM IN TWO PLACES. HE SPENT 5 DAYS AT PRIMARY CHILDREN'S HOSPITAL IN SLC, UT. *TR