Thanks for your reply adam! The solo was indeed played by David Nelson using a B-bender fender on the studio version. I think Garcia plays it live, not entirely sure as I cant find a video of his hands during that song.
Its frustrating for those trying to learn it because of that guitar haha, but I cant complain it adds to the richness of the Dead's sound. I am curious as to wether or not it can be played with out it?! Im sure it can. Maybe thats why jdarks tab is the way it is?