Marine G503 doing ambulance duty. This vehicle is assigned to headquarters, 2nd Marine Division, 2nd Pioneer Battalion.
The 2nd Division was originally formed as an Engineering Battalion early in WW2 and fought in the battles for Guadalcanal, Tarawa, Saipan, Tinian, and Okinawa.
The picture is likely late 50's after a name change from the 2nd Engineer Battalion to the 2nd Pioneer Battalion and a relocation to Camp Lejeune, NC.
Interesting set of field mods to allow the jeep to carry multiple liters. Also interesting to note that this jeep is an early Willys MB "slat grill", serving faithfully circa 1958.
Photo Credit: National Archives