This Scruggs arrangement of Wayfaring Stranger follows the melody arc closely, adding a lot of bluesy and modal touches throughout. There is a slight re-harmonization(chord change). The chord goes to an F at the end of the verse. This helps add to the modal and bluesy feel. It also makes the impact of going to the D7 more powerful and unique. Whenever you change the chords you need to change the melody so the notes match that chord, and vice-versa. We've done that here.