Peyton Manning donned the Tennessee Orange once again on Sunday ... throwing on shoulder pads and his old No. 16 threads for Morgan Wallen's big concert in Knoxville!!
The country music superstar had a gig at the Volunteers' Neyland Stadium ... and as he made his way to the stage for the set, the two-time Super Bowl-winning quarterback helped walk him out.
View this post on Instagram
Manning -- who tore it up for the Vols in the mid '90s -- understood the assignment .