[Jeffhs]

As late as the 1970s, some FM stations were still identifying with their call signs and channel number. I live near Cleveland and remember one such station on 105.7 MHz identifying as WKYC-FM, 105.7, channel 289, Cleveland, in the mid to late 1970s.

FWIW, the station was operated by NBC (the radio network was still in existence then; it was disbanded, however, some time [read decades] ago) at that time (1955-65 and 1965-'80). The AM station is now WTAM 1100, the FM is now WMJI, and the TV station is still WKYC-TV; however, the AM and FM stations changed owners and call signs several times since the '70s and are now, respectively, talk and classic hits (a.k.a. oldies) stations. The television station is still WKYC-TV; however, it is now owned and operated by Tegna Media and has been an NBC-TV affiliate since its initial sign-on in 1948.