This photo was taken from a booklet published and distributed by the AF Museum Foundation, Inc.

The L-20A "Beaver" (aka U-6A after 1962) was manufactured by deHavilland Aircraft of Canada, Ltd.
More than 200 L-20As went into USAF inventory between 1952 and 1960 to be flown in
utility transportation and liaison roles.
SPECIFICATIONS
Wing Span:  48 feet
Length:  30 feet, 4 inches
Height:  10 feet, 5 inches
Weight:  5, 100 pounds loaded 
Armament:  none but with provision for two racks beneath each wing capable of carrying one 250 pound bomb
or chemical tank on each rack.
Engine:  single Pratt and Whitney R-895, 450 horsepower
Crew:  1 (plus 5 passengers)
Cost:  $45,000.00

PERFORMANCE
Maximum speed:  163 miles per hour
Cruising speed:  120 miles per hour
Range:  455 miles
Service ceiing:  20,000 feet

The principal mission of the USAF L-20a was aerial evacuation of litter and ambulatory patients.
Other missions included courier service, passenger transport, light cargo hauling, reconnaissance, rescue,
and aerial photography.
The L-20A saw USAF service in both the Korean Conflict and Vietnam War.  
Now this model can be seen in museums 
 

The Air Force Museum and when you get there, click on "fighter A/C" and then to the "F-4C" and you will be viewing the very aircraft Sergeant Cook worked on while at Ubon in Thailand but that's another story folks!