VEHICLE WAS COMPLETELY STOPPED WHEN REAR-ENDED BY CHEVY SUBURBAN TRAVELING APPROX. 50 MPH. CAR WAS THRUST FORWARD OVER 50 AND STRUCK REAR-END OF PICKUP TRUCK. DRIVER SIDE SEAT BROKE ON IMPACT-CAUSED SEAT TO SLIDE COMPLETELY FORWARD. NO AIR BAG DEPLOYMENT. DRIVER WAS RESTRAINED IN SEAT BELT, BUT STILL HIT HEAD ON WINDSHIELD RESULTING IN BRAIN INJURY. *JB