@whatthefluther – Like many stutterers, Mel Tillis could sing without stuttering, as well as whisper. This is due in part to changes in the way the brain “talks” to the vocal cords and also to being familiar with the words instead of initiating speech de novo.
And Jim Nabors, who was the uncle of our neighbors, did indeed have a beautiful and highly trained singing voice. However, his normal voice was actually lower than the high pitched register he used as Gomer Pyle, and lacked much of the accent that was part of what made Gomer so funny. In fact, that accent was something he developed for an early cabaret act where he sang and talked in multiple voices. He didn’t visit often because he had terrible asthma as did several of his nieces and nephews.