When I tried Pene's link to the Grateful Dead version, i got a "URL Not Found" message.

I can recall one verse (one of my favorites) regularly sung by the GD that isn't found among the Digitrad lyrics. Let me lay it on y'all:

I wish I was a headlight / On some northbound train (2x)
I'd shine my light through the cool Colorado rain.

I'm sure that this is an old, old song with many different and equally valid verses, and the Dead's selection of three or four verses is as "authentic" as anyone else's. Certainly, Jerry Garcia was as true a folkie as anyone else during his younger years; he undoubtedly knew the Judy Henske version (certainly from the recording, probably from live performance as well) and, as a serious banjo picker and scholar, he probably knew at least one other version as well, from the bluegrass tradition.