Complex sentence: The Blackhawk debuted in January of 1970 at the Waldorf Astoria in New York City, and approximately 500-600 had been manufactured by the time production ended in 1987.
Split into simpler sentences: The Blackhawk debuted in January 1970 at the Waldorf Astoria in New York City. Approximately 500--600 had been manufactured by the time production ended in 1987.