Well--first off, the pounding bass note is a D--the thing that is confusing is that this tune is played in D down tuning, which is to say, the low E string is lowered to a D, and then pounded unremittingly for the whole tune--The chords are simple--

First) it starts on a D sus4(which is a D chord with the pinky holding down the G string--O-O-O-2-3-3)

Second) and then falls back to a D-- O-O-O-2-3-2--it does this over and over and over and over, till it gets to the single note passage,

Third)which is really an arpegiated D7 chord--D-D-F#-A-C(I played it starting with the D on the fifth fret of the A string, then to the F# on the fourth fret of the D string, then to the C on the fourth fret of the G string)

Fourth) followed with a G chord

Fifth)to that far out sounding chord which is really just a most of a G9 chord O-O-9-10-10-10

Sixth) it comes round to a plain old Em, a plain old A7, and back to the Dsus/D business.

At the end of the last verse, after it goes from Em to A7 instead of going right to the D business, it goes F#m/Bm/Em/A7 twice before it goes back to the D thing--

Before I forget, the D thing is four counts of Dsus4m followed by 4 counts of D--

I once saw Joachim Young and his band do the D thing for all of 20 minutes, while different people did solos--amazing that you can actually get payed good money to do something that easy, but....

If you PM me, I can send you an MP3 of the Miller version so you can hear it all--