World War II half-track use
In America, 43,000 Half-Tracks were produced by three primary manufacturers; the largest being the White Motor Company, the original designer, with a total of 15,414 accepted by the War Department. The other manufactures, Auto Car built 12,168 and Diamond T a further 12,421. These designs were produced under license in Canada, and were widely supplied under the Lend Lease program, with 5,000 supplied to the USSR alone.
The fourth manufacturer of American-made half-tracks was the International Motor Truck Corporation division of International Harvester. IH built approximately 12,853 half-tracks, which were shipped to Europe for use by British and French Allied troops. In 1942, they produced 152 M5 units and 5 M14 units at the Springfield Works; in 1943 they produced 2,026 M9 units, 1,407 M9A1 units, 4,473 M5 units, 1,600 M14 units, and 400 M17 units, all at the Springfield Works; in 1944 they produced 1,100 M5A1 units and 1,100 M17 units also at the Springfield Works; and in 1945 they built 589 M5A1 and 1 M5A3 units at Springfield Works. The IHC half-tracks differed visibly from the White, Diamond T, and AutoCar units in several ways. The IHC units had flat front fenders instead of fenders with compound curves; used the International Red Diamond 450 engines instead of the Hercules 160AX engines used by the other manufacturers; used IHC Model 1856 4-speed transmissions instead of the Spicer 4-speed transmissions used by the other manufacturers; had IHC Model FOK-1370 front drive axles instead of the Timken front axles used by their competitors; used IHC Model RHT-1590 axles in the read instead of the Timken axles used by their competitors; and were constructed with fully welded armor with rounded rear corners instead of the bolted armor with square corners used by the other three manufacturers.
In August of 1944, Allied forces liberated Paris, France. The first vehicle to enter the city was an M3 named "España Cañí" and driven by Spanish soldiers fighting under the French tricolor. There followed several days of parades in late August. One parade of 25 August 1944 was down the Champs Elysees, with Charles deGaulle leading throngs of Parisians, and French soldiers driving IH half-tracks.
Armored personnel carriers
M3 - White Half-Track with White 386 cu in (6,330 cc) 160AX engine. Fitted with either an M32 anti-aircraft machine gun mount or a pedestal mount, both featuring an M2HB machine gun.
M3A1 - Any vehicle with the improved M49 machine gun ring mount over the right hand front seat. Between 1942 and 1943 all M3 Half-Tracks (standard and A1s) were continually upgraded. These improvements included a number of drive train, engine, and stowage improvements.
T29/M3A2 - Developed in 1943 to combine features such that existing M2 and M3 production could be switched to a common vehicle. Came at a time where the need for additional half-tracks turned out to be not as great as projected. The M3A2 was, therefore, not produced.
M3E2/M5 - International Harvester Half-Track, externally virtually identical to the M3, but with 450 cu in (7,400 cc). IHC RED-450-B engine, different drive train and fuel and electrical system. In fact, only the chassis, bogies, track, idler and drive sprockets, wheels, winches, transfer case, rollers, and machine gun mount were interchangeable. The M5 is heavier than the M3, due in part to heavier armor. Its rear body sides were in one piece, rather than bolted. The M5 was primarily for Lend-Lease, to Britain, Canada, France, and the Soviet Union.
M5A1 - As for the M3A1, an M5 with the M49 machine gun mount. It could fit one .50-caliber (12.7 mm) and two .30-caliber (30.06) machine guns. The IHC models had a slightly lower top speed (only 42 mph (68 km/h)) and lower range (125 mi (201 km)) as well.
T31/M5A2 - Similar in principle to the M3A2, a vehicle developed by the US Ordnance Department to combine the production of the M5 and M9 into a single vehicle. As with the M3A2, the projected need was never seen, and this version was never produced en masse.
M9 - Same as the M5, with stowage arranged as in the M2 halftrack, with access to radios from inside (as opposed to outside) and rear doors, plus pedestal MG mount.
M9A1 - Same as M9, with ring mount and three MG pintles.
T12/M3 75mm GMC - M3 based Gun Motor Carriage equipped with the M1897A5 75 mm gun. These guns were fitted with the gun's M2A3 ground carriage and its gun shield. Later variants featured a purpose-built gun shield (59 rounds).
M3A1 75 mm GMC - The M2A2 gun carriage was substituted for the A3, as stocks were exhausted. Later variants featured a purpose-built gun shield.
T12 HMC - M3 based Howitzer Motor Carriage equipped with the 75 or 105 mm Pack Howitzer by the US Marine Corps.
T48 57 mm GMC - M3 based Gun Motor Carriage equipped with the M1 57 mm gun, an American copy of the British QF 6 pounder anti-tank gun. A total of 962 T48s were produced during the war. Of these, 60 were supplied under lend lease to Britain, and 650 to the USSR - who called it SU-57 (99 rounds)
T30 75 mm HMC - M3 based Howitzer Motor Carriage equipped with the M1A1 75 mm howitzer in a simple box mount (60 rounds). Used by the US Army. Also provided to the Free French Army, later used in Indochina.
T38 105 mm HMC - M3 based Howitzer Motor Carriage equipped with the M3 105 mm howitzer. Cancelled with the success of the T19.
T19 105 mm HMC - M3 based Howitzer Motor Carriage equipped with the M2A1 105 mm howitzer (8 rounds).
T19/M21 81 mm MMC - M3 based Motor Mortar Carriage equipped with the M1 mortar (81 mm)(97 rounds), designed to allow the mortar to be fired from within the vehicle.
T21 - M3 based mortar carrier fitted with a 4.2 inch mortar. Never adopted.
T21E1 - The T21's mortar could only fire rearward as with the M2 based M4 MMC. The T21E1 reoriented to the mortar to fire forward.
T1E4/M13 MGMC - M3 based Multiple Gun Motor Carriage equipped with the Maxson M33 mount with 2 M2HB machine guns (5,000 rounds). The T1E4 prototypes had the hull sides removed for easy of working with the mount. These were reintroduced on production M13s. This was a development of previous T1s that had all been based on the M2 Half-track Car.
M14 MGMC - M13 MGMC variant, based on the M5 chassis. Supplied under lend-lease to Britain (5,000 rounds).
M16 MGMC - M3 based Multiple Gun Motor Carriage equipped with the Maxson M45 Quadmount (more specifically the M45D) with 4 M2HB machine guns (5,000 rounds).
M16A1 MGMC - Standard M3 Personnel Carriers converted to Multiple Gun Motor Carriages by removing rear seats and installing a Maxson M45 mount (more specifically the M45F, which featured folding "bat wing" gun shields on both sides of the mount over the machine guns). These vehicles are easily identified by the lack of the folding armored hull panels found on purpose-built M16s.
M16A2 MGMC - M16 MGMC variant, basically M16s brought up to M16A1 standard and with the addition of a rear door to the hull compartment. For existing M16s, this essentially meant a replacement of the M45D mount for the M45F mount.
M17 MGMC - M16 MGMC variant, based on the M5 chassis. Sent under lend-lease to USSR (5,000 rounds).
T58 - Similar to the M16/M17, the T58 featured the Maxon quad-mount fitted to a special electric powered turret. Prototype only.
T28E1 CGMC - M3 based Combination Gun Motor Carriage equipped with one M1A2 37mm autocannon (240 rounds) flanked by 2 M2WC machine guns (3,400 rounds). The original T28 had been based on the shorter M2 Half-Track Car chassis.
M15 CGMC - T28E1 variant, equipped with an armored superstructure on the turreted mount to provide crew protection, and switched to M2HB machine guns.
M15A1 CGMC - Reorganization of the weapons, with the M2HB machine guns being fitted under the M1A2 37 mm autocannon instead of above as on the M15.
T10E1 - Variant to test the feasibility of mounting US made copies of the Hispano-Suiza HS.404 20 mm cannon on modified Maxson mounts. All were later rebuilt as M16s. The original T10 was based on the shorter M2 Half-Track Car chassis.
40 mm Experiments - Various attempts were made to mate the 40 mm Bofors L/50 gun to the M3 chassis. In all cases the weapon's recoil was too severe or the mounting too heavy, and the attempts were finally stopped with the adoption of the M19 MGMC on the M24 light tank chassis.
T54/E1 - Tested in 1942, the gun mount quickly proved to be unstable when fired, and the improved T54E1, which also added a circular armored shield and rear armor to the vehicle, could not fix the inherent problem. Prototype only.
T59 - A development of the T54/E1, fitted with outriggers to help stabilize the vehicle during sustained firing. Still proved to be too unstable for anti-aircraft use. Prototype only.
T59E1 - T59 fitted with the T17 fire control system. Prototype only.
T60/E1 - Similar to the T54 and the T59, but featured two .50 caliber M2 machine guns flanking the 40 mm cannon (the mounting's designation was T65). The T60E1 featured an armor configuration similar to that of the T54E1. Suffered from the same stability issues of previous attempts. Prototype only.
T68 - Perhaps the most radical of the experiments, the T68 featured two 40 mm cannons, one mounted on top of the other, plus a stabilizer on top of the two guns. The recoil force proved to be too much for the mount, and the idea was abandoned. Prototype only.
M15 "Special" - Field conversions by US Army depots in Australia of standard M3s, not M15s, fitted with turreted 40 mm Bofors L/50 guns. These were the only successful mating of this weapon to the M3 chassis, and were used more for direct fire support than for anti-aircraft purposes.