The Type 74 was developed to a Japanese Ground Self-Defense Force (JGSDF) requirement for a 105mm-armed self-propelled howitzer. It was built atop the chassis of the Type 73 Armored Personnel Carrier (APC) that appeared in 1973 with production reaching over 330 units. The Type 74 was not adopted in large numbers with only 20 being produced. Design work on the vehicle began in 1969 and resulted in serial production from 1975 to 1978. Despite its 1970s origins and limited production, the Type 74 is reportedly still an active section of an JGSDF artillery regiment.
The Type 74 ended as an 18-ton vehicle built of a configuration long-established by self-propelled guns elsewhere. The included an armored hull with well-sloped glacis plate, the driver seated front-right, and the powerpack at the front-left. The forward installation of the engine opened the rear of the hull for placement of a turret ring and accompanying turret mounting the primary armament. Both hull and turret were then used to house projectiles and charges. The vehicle crew numbered four and was made up of the driver, commander, gunner and loader. Armor construction was primarily of aluminum. Dimensions included a length of 20 feet, a width over 9 feet and a height to turret top of nearly 8 feet. The chassis design stemmed from work by the Komatsu concern.
The running gear included five double-tired road wheels to a hull side arranged in a track-over-wheel configuration. The drive sprocket resided at the front with the track idler at rear and no return rollers were featured. Power came from a Mitsubishi 4ZF 4-cylinder diesel-fueled engine of 300 horsepower. This provided the vehicle with a top road speed of 30 miles per hour with an operational range out to 185 miles on internal fuel. The hull sat atop a torsion bar suspension system for the needed cross-country capabilities.
Japan Steel Works headed the design and development of the power-assisted turret and its accompanying main gun - this being 105mm in caliber. The weapon was of good quality and intended for indirect, long-range barraging of target areas. The loading function was handled manually by a dedicated ammunition handler crewman which joined the commander and gun layer in the turret section. The gun featured a fume extractor along its midway point and a large muzzle brake at its business end. A thick gun mantlet protected the base of the gun from enemy fire. Local defense was handled by a trainable 12.7mm Browning M2HB heavy machine gun fitted to a mounting over the right-side turret hatch. This weapon could be effectively used to counter low-flying aircraft, light-armored vehicles and enemy infantry. When buttoned down, the vehicle crew held access to several vision blocks for situational awareness.
The vehicle spent a fair amount of time in the design stage from 1969 onwards. Pilot vehicles emerged by 1974 and these were tested at length to prove the vehicle sound for use by the JGSDF. After approval, it was formally adopted in 1974.
The JGSDF also took on another SPH system in October of 1975, this becoming the Type 75 and fielding a larger-caliber 155mm gun system and was more akin to Western designs such as the American M109 and British AS90. The Type 75 was produced in far larger numbers, totaling 201 vehicles from 1975 into 1988, and were built atop the chassis of the Type 74 Main Battle Tank.
The Type 73 Armored Personnel Carrier of the Type 74's foundation is also the basis for the Type 75 130mm tracked Multiple Launch Rocket System (MLRS) vehicle. This was introduced in 1975.