Also, did you know that Solidarity Forever uses the tune from John Brown's Body?
A lot of songs use that tune. As Utah Phillips put it: The wobblies liked to steal the hymn tunes because they were pretty, and changed the words so they made more sense.
I own a reprint copy of the Little Red Songbook and each song instructs you which existing song to sing to the tune of. Btw great cheap book to buy for anyone interested
btw a LOT of songs use that tune. Getchan recently uploaded a Maoist who wrote a song to the tune calling back to the start of the Cultural Revolution, written during the period of marketization
https://www.youtube.com/watch?v=QJ0cFXH02nM