Steve demonstrates his signature Music Man guitar in this video. According to this page of his website, "The history of this unique instrument goes back to Steve's college days. During that time, Steve crafted a guitar for himself, combining the elements for his ideal instrument: a Fender Telecaster body, Stratocaster neck, Gibson Tune-o-matic bridge, a set of Gibson frets, a 12-string tailpiece (make unknown), and a group of pickups (also unknown). He called it the Frankenstein Telecaster, and constantly revised and improved it over the years. In 1986, Steve was approached by Musicman to collaborate on creating a production model. This guitar has since expanded to several models, and over 50 choices and combinations of finishes."
According to Vintage Guitar interview, Steve used his signature model with Dixie Dregs.