Complex sentence: WBLS was often the number one FM station in New York from 1974 to 1978, competing often with the original WKTU (then at 92.3 FM), a dance/disco station whose music rosters included black artists.
Split into simpler sentences: WBLS was often the number one FM station in New York from 1974 to 1978. During this time its main competion was the original WKTU (then at 92.3 FM), a dance/disco station whose music rosters included black artists.