What a lovely version of Libba Cotten's tune. Nice variations.
Like many folkies, I learned guitar fingerpicking in the early sixties from Libba's first record Negro Folk Songs And Tunes and I believe Freight Train was the first tune I learned.
Though I haven't played it for a few years, I'll try to revive it and apply some of your (Ukulelezaza's) variations to my guitar playing.