[4] These tanks had seen heavy use during World War II, and after their handover to Japan they required total mechanical overhauls in only a few years.

Since a large amount of parts were being consumed on the Korean peninsula, it was necessary to produce the spares used in Japan domestically, and procedural knowledge of American style tank design and maintenance began to accumulate.

[4] During the Korean War, the performance of the T-34 and M26 Pershing had made it clear that new Japanese tanks would require 90mm main guns.

The driver sits at the front right of the hull, with a hatch immediately above him, and three vision periscopes covering the forward arc.

The suspension is a torsion bar system with the first, second and sixth road wheel fitted with hydraulic shock absorbers.

[3] At the beginning, Japanese engineers intended to adopt the cross drive system studied by observing the repair work of the M47 Patton of the American military which was done in Japan, but did not realize it.

Additionally, due to the mountainous landscape of Japan, it was unlikely that long range engagements would occur frequently and it was thought that a 90 millimeter gun would be sufficient.

[6] The commander's cupola has four vision blocks, which are angled upward, and a one-meter base stereoscopic rangefinder with x7 magnification.

[6] The initial production rate was low, with only ten tanks produced in 1961 and 1962, increasing to twenty in 1964 and thirty in 1965 and 1966.

[8] During this period, the Type 61 received minor upgrades in the form of infra red searchlights and/or smoke dischargers.