In 1949 the US Army issued a requirement to equip airborne troops with a light tank destroyer that could be transported by the existing aircrafts. The idea was to achieve a very light and mobile vehicle armed with a gun capable of destroying a tank with a single shot. For this task, a powerful 90mm gun was installed on an unarmored aluminum chassis that allowed perfectly the use of the “shoot and scoot” tactic, leaving the enemy wondering what had hit them. Cadillac Motor Car Division of General Motors introduced a prototype designated T-101 in the early 1950s which after undergoing tests was approved for service and manufactured between 1953 and 1959 under the designation M-56 Scorpion.
M-56 SCORPION gallery and more info