Open E, just kinda exploring what kind of chords are in the key and fell into this song..... I'm sure you already know but it's E b e g# b e ... I'm not very familar with how to play much in open E but there are people like Duane Allman, Derick Trucks, Johnny Winter, Elmore James who played a lot in that tuning.... Sorry it took so long to reply I overlooked the comment.. but now I'm back on track ;9)