The crews participating in this operation demanded further changes. This includes modification of the suspension to increase self-cleaning from mud, a change of the rear turret MG position and a lager commanders cupola. The necessary changes were made until 1934. The upper part of the suspension was remodelled by removing one return roller to increase the space between the remaining rollers where the mud could fell off. The suspension armour plates received a sloped upper part to let the mud slide off easier. The turret was remodelled, too. A large cylindrical commanders cupola was installed and the turret MG was moved from 180° position to 210°position in an armour extension. Several minor changes were also done. The changes were also implemented in the serial production leading to more intermediate versions. In late 1933 Mitsubishi was able to finish the development of a 120 hp 6-cylinder Diesel engine. This engine was implemented in the Type 89 Medium Tank until 1934 which made several changes regarding cooling air intakes and transmission necessary. In addition IJA decided to standardise the crew positions in their tanks. So the drivers and bow gunners position in the Type 89 Tanks had to be exchanged which was also done in 1934. With the beginning of the production of the Diesel-equipped tanks the gasoline version received the additional designation "Kou(A)", the Diesel-engined "Otsu" But the Diesel engine production never reached the same numbers as the tank production, gasoline engines still had to be used until the end of the production in 1936. A total of 278 Type 89 Medium Tanks Kou and 126 Type 89 Medium Tanks Otsu were built. Type 89 Medium Tanks were involved in almost all IJA and IJN tank unit operations until 1940. They did a good job in their intended task, infantry support. From 1939 on they were replaced by the successor, the Type 97 Medium Tank Chi-Ha. The Nomonhan Incident in 1939 showed that the Type 89 Medium Tanks were outdated regarding armour and armament but they were used until 1945, finally as mobile pillboxes in the Philippines and Burma. After the war the Type 89 Tanks were still used by local chinese forces, the indonesian liberation forces and french forces in Indochina. french Type 89 Medium Tank in Indochina Data (version Ko / version Otsu): vehicles built: 278 / 126 battle weight: 12 (metric) t early version, 14 (metric) t late version crew: 4 men length: 4300mm, 5750 mm with ditching tail width: 2180 mm height: 2560 mm ground clearance: 480 mm track width: 305 mm trench crossing capability: 2000 mm, 2500 mm with ditching tail climbing capability: 34° maximum vertical obstacle: 840 mm engine: 6-cylinder Daimler gasoline / 6-cylinder Mitsubishi Diesel power: 118 hp at 1400 rpm / 120 hp at 1800 rpm maximum speed: 25 km/h on roads fuel capacity: for an operational time of 10 h cross-country range: n. a. transmisson: 6 forward, 1 reverse power/weight ratio: 10 HP/t / 8,57 hp/t armament: 1 X Type 90 57 mm Tank Gun , 2 X Type Taisho 3 6,5 mm MG, later Type 91 6,5 mm Tank MG armor strength turret front 15 mm @ 80 ° sides15 mm @ 80 ° rear 15 mm @ 90 ° Roof 10 mm @ 0 ° superstructure front 17 mm @ 75 ° sides 11 mm @ 90 °, upper part @ 35 ° rear 8 mm @50 ° Roof 6 mm @15 ° The only remaining operational Type 89 Medium Tank Otsu at JSDF Tank School Tsuchiura, Japan Yours tom!