Serial number range: 2507601-2747630 (1972-1975, approx. 54,350 produced). Production by year: 1972: #2507601-2554550 (6,000 units); 1973: #2558551-2640600 (30,000 units); 1974: #2674701-2721000 (12,350 units); 1975: #2741631-2747630 (6,000 units).