Although I remember this tune from my youth, I have never played it. I checked you tube...the Booker T and the M.G.'s version is removed. Below there is a very good version by a group out of Michigan.
I believe klasaine is technically correct on everything except the G/C double stop. That actually should be Ab/Db, I think, in keeping with the key of Bb and the blues notes. The slight bend of these takes the notes is a tension builder.
As to the turnaround, much R&B and soul guitar lives on partial chords. Complete chords get in the way of the movement of the various instruments.
I think this guitarist is working some double stops through this turnaround.
The 7th out of that F7sus chord mated with the sustained 4th(8th fret,3rdst with the 11thfret/2nd st) works well going into the 3rd of the Db7 mated with the flatted 7th (10th fret/3rd str with the 12fret/2nd str). IF you fall down a
1/2 step to the 11thfret/3rdstr with the 11thfret/2nd str, you have the Gb7; and this works well with the 3rd and 5th out of the Eb chord(12th fret 3rd str with the 11th fret 2nd str). The guitarist in this group gives that one a shake for some tension that releases back into the Bb7 chord. The guitarist in this group doesn't spend much time playing full chords.
I only found a portion of the real deal recording to listen to, but I might guess that Cropper wasn't playing too many 6 note chords through this one, either. The bass and the organ can easily find space to grow when a guitarist takes this approach.
There's always more than one way to get around the bend....
These Michigan fellows do a good job of this one, imo.
http://www.youtube.com/watch?v=8RSkUW4hIxU