Elliott's RRB is tabbed in the old "Young Folk Songbook" from abt 1962, though it may be a little hard to find these days. I think there is a tab, based on Hobart Smith, in the "New Lost City Ramblers Songbook" (aka "Old Time Stringband Songbook"). Happy Traum gives a generic tab version in the 60s Oak book on fingerpicking styles for guitar, whose title I don't remember exactly. (Maybe it is "Fingerpicking Styles for Guitar.")

If ya just want the chords, the standard ones are

[C]Early one morning, sky was rain
[E7]Round the curve come a [F]long freight train,
[C]Ride, [G7]ride, [C]ride.

You can also do Harvey Hull and Cleve Reed's "Original Stackolee Blues" and Crying Sam Collins' "Lonesome Road" to the same arrangement and nearly the same pick, though the melodies vary a bit.