Acquired by the US Marine Corps, the CTL-6 was an iteration of Marmon-Herrington's CTL-3 with a new engine and vertical volute spring suspension bogies akin to those found on the light tank M2. The new powerplant forced the engine decking to change to a horizontal profile from the earlier sloped arrangement. The engine louvres were .25" (.64cm) thick.
Estes, Kenneth W. Marines Under Armor. Annapolis, MD: Naval Institute Press, 2000.
Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
Spoelstra, Hanno. "Marmon-Herrington Military Vehicles: Tanks." Marmon-Herrington Military Vehicles. 21 Feb 2020 <http://www.marmon-herrington.webs.com/tank.html>.
Nuyt, A.F. "tanks." Overvalwagens! 21 Feb 2020 <https://web.archive.org/web/20060414173105/http://www.overvalwagen.com/tanks.html>.
Kirk, William. "U.S. Light Tanks." TANKS! 13 Feb 2003. 21 Feb 2020 <https://web.archive.org/web/20120212011858/http://mailer.fsu.edu/~akirk/tanks/UnitedStates/lighttanks/LightTanks.html>.