Prior to Florida last year, the last time Utah played an SEC team in the regular season was 1984 @ Tennessee (21-27 loss). They also played @ Tennessee in 1979 (18-51), @ Florida in 1977 (29-38), @ LSU in 1976 (7-35), @ Tennessee in 1975 (7-40), and @ LSU in 1974 (10-35).
So the correct answer is that the next time will be the first.
I was thinking about this and could not come up with an SEC team that had ever played in SLC. So, your post confirms that I haven’t totally lost my mind. 🙂
BYU hosted Mississippi State, so at least one SEC team has come to Utah to play.