40 at 40: Twitty's "Desperado Love" established a chart milestone.

Conway Twitty performs at Wembley Arena in England in 1985.

David Redfern/Redferns

Conway Twitty started his music career as a pop hitmaker on the all-format Billboard Hot 100 — his “It’s Only Make Believe” topped the chart in November 1958 — before he found his full voice in country, and the last of his 40 chart-topping titles in the genre came from a songwriter who made a similar format change.

North Carolina-born Sammy Johns earned national recognition when his recording of “Chevy Van” parked at No. 5 on the Hot 100 in 1975, but he followed that by writing his way into the country market. With “Desperado Love,” co-written by Michael, Johns transformed a negative life period into a win. He was about to lose his house, started drinking to numb his depression, then decided to see if there was a song in all of his misery. He felt desperation, brainstormed that into desperado and took off from there.