The T18 howitzer motor carriage, or T18 HMC, was an American self-propelled gun.

Because the Army disliked the high superstructure and nearly vertical armor, the T18 was abandoned in 1942, and soon started a new turreted project, the T41 75 mm HMC, also known as the howitzer motor carriage M8.

[4] The development started in September 1941 with a requirement for a close-support vehicle based upon the M3 Stuart's chassis, but it was made of a mild steel superstructure.

A 75 mm Pack Howitzer was mounted on the right of the glacis plate of the vehicle.

By the time the first pilot model was midway into being completed, the project was canceled since the army disliked the high superstructure, nose weight, and nearly vertical armor.