I've always thought that RJ's recording of "Hell Hound on My Trail" was speeded up. I've just been listening to it again and the vibrato on the upper regions of the voice - to me - still has hints of that "Chipmunk" effect and sounds somehow unnatural. The speeding-up theory, in this instance and on listening evidence alone, seems to have some credence.

Checking through the timings on my collection of his songs, the longest track is "I Believe I"ll Dust My Broom" at exactly 3 minutes. The next longest is "They're Red Hot" at 2:59. No track is longer than these two.