Arrived at MCRD Parris Island 07/12/1971. Assigned to 3rd Battalion, Platoon 365. Don't remember which company. On first day of the two week maintenance detail, I ran into an air conditioning unit sticking out of the maintenance shed while trying to jump over the first bench in a row of about five benches. I was knocked out, dislocated my left shoulder and suffered a light concussion. I was taken to the medical unit, my left arm put into a body sling and was put on no duty for the next two weeks. I am looking for any one who remembers this incident.