I hang on the F to G chords. Listen to the album for a simplified riff when Phil plays the F note at the eigth fret and ends the riff with what sounds like a hammer-on* from F over C at the tenth fret to the G over D at the twelth fret and back to the F note at the eighth fret for the one. As the song evolves in live performance Phil expanded/improvised around this theme but it still centers around the F to G.
Tempo = 60
/ / / /
Hope this helps!
Let me know if you have any more questions. This is my favorite Grateful Dead tune to play on bass.