Years ago, when I was heavy into torrents and collecting bootlegs cd's I used this site as I am a big Dylan Fan. There are literally thousand of bootleg CD's out there for Bob, I actually have at least a hundred of the best bootlegs by him . These are called ROIO's , Recordings Of Indeterminate Origin, often recorded by a fan at a show, the best are taken from the soundboard by some one working the show or from a TV or radio broadcast. This site gives a comprehensive listing of what is out there http://www.bobsboots.com/
Edit: purist traders of this material don't use lossy mp3's , all my stuff is in .flac format and unfortunately Bob's Boots appears to have not been maintained in quite a few years, a lot of it is broken
Further edit: My computer still remembered my user and password for this site and discussion group which should provide some more sources of Dylan stuff should you care to join https://www.expectingrain.com/