From Nissan press:
1966 Silvia: This is the special, semi-custom made car based on the engine and chassis of the Fairlady 1600 (SP311). For this reason, although the manufacturing period was approximately 3 years, from March 1965 to June 1968, not many units were produced. The price tag was 1.2 million yen. It became well known as a result of being used by the police for patrolling the Daisan Keihin Road.