|Date of first acceptance||June 1936||Total acceptances||5|
|Manufacturer||Marmon-Herrington Co.||Crew||2 men|
|Three .30cal MG||Ball mounts in hull front||Manual||Manual|
|Engine||Lincoln 12 cylinder vee gasoline|
|Type||Road wheels||Track return rollers|
|Semi-elliptical leaf spring||2 bogies/track;
2 dual wheels/bogie
|Drive sprockets||Idlers||Shock absorbers||Front drive||Adjustable at rear of track||None|
|Center guide band type|
|Max level road speed||33mph
|Max vertical obstacle||18"
|Max fording depth||40"
The CTL-3 was a turretless vehicle, and the three machine guns were mounted in the vertical portion of its stepped hull front plate. A long, sloping rear deck covered the engine, and the crew sat in a raised box near the front of the tank that provided three viewing ports on its front, two on the rear, and one on each side. Driving controls were fitted to both crew stations.
In 1938, the improved CTL-3A debuted with an improved suspension. The original suspension featured a longer leaf spring that supported the first and last road wheels, while the middle two were sprung on a shorter leaf spring. The CTL-3A reworked this to incorporate two long leaf springs behind a frame. The CTL-3A was powered by a 124hp Hercules 6-cylinder engine and weighed 10,900lb (4940kg). Five CTL-3As were delivered to the Marines in June 1939, and the original five CTL-3 tanks were brought up to CTL-3A standard.
At least five CTL-3s were rebuilt in 1941 with a new vertical volute spring suspension similar to that found on the M2A4 light tank. Two two-wheel bogies were installed on each side, and a single return roller was mounted between them. The bogie frames had track skids mounted on their tops. A 14-tooth front drive sprocket turned the outside guide tracks which were made up of 54 shoes on each side. These tanks were designated CTL-3M.