When I've played this tune I've just used a regular diatonic harp in second position and made up a harp part. I made no effort to copy the bass harmonica part.
The original bass harmonica part in that tune was done by Charlie McCoy and it was on a double tiered bass harp, probably the toughest harmonica to play of them all. ---------- Sincerely, Barbeque Bob Maglinte Boston, MA http://www.barbequebob.com CD available at http://www.cdbaby.com/cd/bbmaglinte
There's actually another version of this tune by Simon and Garfunkel that has an additional verse.
Last year, there was a guy I'd run into at an acoustic open stage who did this tune. Acoustic jamming isn't really my thing, but I like playing with the band leader who ran the jam and he played a hollow body electric guitar and had a guy with him who played electric bass and keys, so I'd bring my Princeton Reverb and play along with them and then play along with whatever other players who'd let me play.
Anyway this guy who sang "The Boxer' could really play and sing. i love the tune, but had never had a chance to play it before, and I'd get a chance to play with him it when he showed up at the open stage. He sang the extra verse so i started hunting around on the web until i found out it was actually from the version Simon and Garfunkel sang on Saturday Night Live.