NASHVILLE — Reggie Young, a prolific studio guitarist who appeared on landmark recordings by Elvis Presley and many others and played a prominent role in shaping the sound of Southern popular music in the 1960s and ’70s, died on Thursday at his home in Leipers Fork, Tenn., just outside Nashville. He was 82. His wife, Jenny Young, said the cause was heart failure. Young played guitar on hundreds of hit recordings in a career that spanned more than six decades. Among his best-known credits are the Box Tops’ “The Letter” and Presley’s “Suspicious Minds,” both #1 singles in the late...