It had became clear that the combined weight of the turret, radar, and computer systems was too heavy to allow the vehicle to maintain the desired level of mobility. Various tests were carried out using the completed prototype vehicle. Mounting the new twin 35mm autocannon system into the Type61 chassis.

The second prototype of the SPAA project. Oerlikon provided Japan with a design proposal for a set of 35mm autocannons on a rotatable turret design which would house a search and track radar. The Japanese Self Defense Force worked out a cooperation agreement with Oerlikon Contraves, a renowned anti aircraft gun manufacturer of the era. In 1978 the decision was made to again attempt to base a new SPAAG off the Type 61 main battle tank chassis. No attempt to find a suitable replacement would be attempted for six years. Due to this unwanted outcome, the project for a new SPAAG was canceled. Ultimately, it was rejected by the Self Defense Force for its turret being 'excessive' and unreliable. The first prototype was completed in 1972, and was put through various trials. While the tank was a failure to the military, the use of its chassis for an anti aircraft tank could have given it a new lease on life Japan had already started working on a new main battle tank project to replace it, and the choice seemed to be the best use of resources at the time. Their logical conclusion was to use the chassis of the Type 61 main battle tank as the starting point. In the late 1960s the the Technical Research Department came together to conceptualize a new SPAA-like vehicle to meet the needs of the military. Faced with the refusal of the US to supply more modern vehicles, the Japanese decided to initiate their own SPAAG program during the late 60's. These concerns were voiced to the United States over the years ,however the US simply ignored these requests as well as Japanese requests for modern armor. Even for the Japanese Self Defense Force, the short ranged 40mm Bofors guns were inadequate and couldn't meet the requirements needed to successfully engage and destroy modern aircraft of the era. During their initial time spent in the SDF, they were used as trainers for anti air tactics and methods of engagement. These lend lease tanks were short lived, however.

Japanese tanks modern 2017