Serial number range: 2505101-2917000 (1972-1978, approx. 48,800 produced). Production by year: 1972: #2505101-2547550 (1,100 units); 1973: #2570551-2650600 (27,500 units); 1974: #2680701-2721820 (12,500 units); 1975: #2731951-2738450 (3,500 units); 1976: #2763501-2766500 (3,000 units); 1977: #2858601-2859600 (1,000 units); 1978: #2916801-2917000 (200 units).