There is no D in the A part.

Seems to me the logical walk up to D would be Am-Bm-C-C#dim-D

because you would arrive at the D chord at the right time in a ascending chord scale.

I googled it and found about five different versions of the chords. only two agreed...and though I agree it's a GM7, NOT a Bm in the A part... not one of those six versions called for the GM7.

The two versions I found that agreed had Am-A/B C/E D...assuming they mean Am then Am with B in the bass and C with E in the bass...they did not note the timing...how many beats on each chord...but that would have the E overshooting the D.

The only version I found with Hartford himself (CMT video-Tony Rice, Vassar, a GAGGLE of others including a piano player) it was unclear to me. Seems like not everybody was playing it the same way. Roy Huskey Jr was definitely not playing the same chords as Tony rice who is always playing colored chords anyway so who knows what the hell he was playing. I'm not much of a guitar player so I can't just look at the chord shape and tell. I don't have the record any longer.

That's what you get on the internet.