The M5 resulted from the fact that White, Autocar, and Diamond T could not keep pace with the demand for half-track personnel carriers, and was analogous to the M3 half-track. The front wheels on IHC half-tracks could be engaged for cross-country travel as well. M5s differed in several respects from the M3, however. The M5's fenders were flat in cross-section, and the M5 was never fitted with the large fender-mounted headlights. International Harvester used rolled homogeneous steel armor on their vehicles, which allowed plates to be welded together, giving IHC's half-tracks a smoother appearance than the bolted half-tracks. The rolled homogeneous armor could also be formed, and IHC's half-tracks featured rounded rear corners, which contrast to the right-angled corners on the machines with face-hardened armor. Homogeneous armor lessened the chance of injury due to bullet splash and flying cap screws which could be dislodged when hit, but it was not as strong as face-hardened plate. This meant that the armor on IHC's half-tracks needed to be thicker than the face-hardened armor of the M3 to offer the same protection. The M5 was therefore fitted with heavier axles and hull strengthening components, but its performance still essentially equaled that of the lighter M3. The M5's length with the anti-ditching roller was 242.19" (615.16cm). A 2lb (.9kg) CO2 portable fire extinguisher was carried.
The M5A1 was fitted with the .50cal ring mount over the assistant driver's position, and a socket mount for the .30cal MG was attached on either side and the rear of the passenger compartment.
Due to the similarity between the M5and M9A1 half-tracks, a proposal was put forth in February 1943 by Army Ground Forces that the types be combined into a single vehicle. International Harvester Corporation was given three M5s to convert according to plans drawn up for a single half-track body. The new design could be used for different missions by changing the interior radio, etc., stowage, and was armed with an M49 ring mount and machine gun pintle sockets like the -A1 half-tracks. The vehicle was also built with folding rear stowage racks, and ladder-like side stowage racks above the mine racks that could be used to secure the canvas cover over the passenger compartment. This design was standardized as the M5A2 on 2 October 1943 and was set to replace the M9A1 and M5 half-tracks starting on 1 March 1944, but production of half-tracks had been discontinued by that point and only the M5A2 pilots were built.
TM 9-707 Basic Half-Track Vehicles (IHC) (Personnel Carrier M5, Car M9A1, Multiple Gun Motor Carriage M14, and Similar IHC Vehicles). Washington, DC: War Department, 21 May 1943.
ORD 7-8-9 SNL G-147 Organizational Spare Parts and Equipment List, Higher Echelon Spare Parts and Equipment (Addendum) Service Parts Catalog for Car, Half-track, M9A1, Carrier, Personnel, Half-track, M5, M5A1, Carriage, Motor, Multiple Gun, M14, M17. Washington, DC: Headquarters, Army Service Forces, 15 May 1944.
TM 9-2800 Standard Military Motor Vehicles. Washington, DC: War Dept., 1 Sep 1943.
Doyle, David. U.S. Half-tracks: The Development and Deployment of the U.S. Army's Half-track Vehicles, Part one. Ed. Pat Stansell. Delray Beach, FL: The Ampersand Publishing Group, Inc., 2014.
Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
Sola, Samuel, Vincent Bobkowski, and Kara Crocker. Weapon Mounts for Secondary Armament. Santa Monica, CA: G. O. Noville & Associates, Inc., April 1957.
Track Data. Warren, MI: Track & Suspension Laboratory, Components Research and Development Laboratories, Research & Engineering Directorate, US Army Tank-Automotive Center, 23 June 1965.
