Serial number range: 1850001-3059800 (1961-1980, approx. 7,800 produced). Production by year: 1961: #1850001-1901000 (2,000 units); 1963: #1993001-1993900 (900 units); 1965: #2122651-2123650 (1,000 units); 1966: #2216201-2217200 (1,000 units); 1968: #2298351-2298950 (600 units); 1969: #2340801-2342300 (1,500 units); 1974: #2713851-2714000 (150 units); 1975: #2757651-2757900 (250 units); 1977: #2815901-2816100 (200 units); 1980: #3059601-3059800 (200 units).