The three versions I'm familiar with are -
1) that by Steve Goodman, who wrote it, and uses the phrase "old black men"
2) the version by John Denver (the first version I heard) where black is substituted with grey, and
3) probably the most popular version by Arlo Guthrie which also refers to "black" men.

When someone else sings it, you can usually tell wh they nicked it from as the Arlo Guthrie version uses the wrong tune for the phrase "gone 500 miles".