Staff Writer (Updated: 7/22/2016):
As can be expected, the AMX-13 was highly influenced by World War 2 armored warfare doctrine. She was designed around a traditional "track-and-wheel" system allotted five double-tired road wheels per track side, a front-mounted drive sprocket and a rear-mounted track idler. Power was derived from a SOFAM Model 8Gxb 8-cylinder water-cooled gasoline-fueled engine developing 250 horsepower. Capabilities included a top speed of 37 miles per hour and an operational road range of 250 miles while the hull was suspended on a torsion bar system which provided the needed cross country mobility. The vehicle was crewed by three personnel made up of the driver (seated in front hull) as well as the commander and gunner (residing in the turret). An automatic loader negated use of a fourth dedicated crewman and thusly allowed for a more compact turret design. NBC protection was not afforded and night vision equipment was optional.
The unique turret was provided by GIAT (now the Nexter brand) which consisted of an upper and lower turret section assembly, the upper section hinged to operate independent of the lower. This allowed engineers the ability to mount a very heavy main armament to an otherwise lightweight chassis. In this way, the AMX-13 was granted use of a capable 75mm main gun - a weapon based on the German war time L/71 main gun as fired from the Panther Medium Tank (updated to a 90mm main gun in 1966). Internal volume was limited and thusly a noticeable overhang was given to the upper turret section for ammunition stowage. The oscillating turret became the primary design characteristic of only the AMX-13 Light Tank and Panhard EBR armored car designs frontline vehicles - the concept having never caught on in the mainstream design world concerning armored fighting vehicles.
The AMX-13 eventually emerged in many prototype forms to test the validity of various concepts. Some prototypes appeared after operational service was ongoing and these gave rise to over a dozen production variants over the life of the vehicle. Modernization programs served to keep the system capable throughout the Cold War years. Beyond the base light tank forms, the chassis of the AMX-13 also served in the development (and subsequent production) of an armored personnel carrier (AMX-VTT/AMX-VCI) , a 105mm-armed self-propelled gun (AMX-105) and a 155mm-armed self-propelled gun (AMX-155). Other notable versions included the AMX-13 PDP bridge-launcher, the AMX-D armored recover vehicle and the dual-cannon air-defense-minded AMX-DCA armed with 2 x 30mm Hispano-Suiza HS 831 series cannons. A turretless version was developed for driver training.
Operators of AMX-13 (or related products) spanned the globe beyond France and went on to include Argentina, Indonesia, Mexico, Netherlands, Singapore, Switzerland and Venezuela. The French began to retire the AMX-13 series in the 1970s but its reach endured beyond that. Israeli types were used in anger during the 1967 Six Day War though its original 75mm main gun proved ineffective against Egyptian and Syrian Soviet tanks. Some of the Israeli stock managed to find its way to Singapore which enjoyed operation of some 350 examples which, though modernized, are being phased out as of this writing (2012).