75 mm Gun M3 on 75 mm Howitzer Motor Carriage M8 Chassis

Created in January 1943 as a proof of concept, the 75 mm Gun M3 on 75 mm HMC M8 Chassis was an experimental American tank destroyer.

75 mm Howitzer Motor Carriage T18

In early 1941, the Firestone Tire and Rubber Company submitted their proposal for a fully enclosed SPG based on the chassis of the M3 Stuart, designated T18 75mm HMC.

T25 AT (Fake Tank)

The T25 AT is a 'fake' American tank destroyer that mounts a 90 mm or 105 mm gun on the chassis of the T23 medium tank.