Written and first recorded by Tim Moore (1975).
Hit version by Bay City Rollers (US #28 1976).
From the wiki: “‘Rock and Roll Love Letter’ is the second single from American Tim Moore’s second album, Behind the Eyes. It was written by Tim Moore. Tim Moore’s original version was not successful. It was later covered by the band Bay City Rollers, and that version became a Top 40 hit.”
Bay City Rollers, “Rock and Roll Love Letter” (1976):