Sammy Hagar is well known in the music industry, especially for his part in the group Van Halen. A lot of Boston fans don't know this, but Boston's guitarist Gary Pihl was Sammy's guitar player before Hagar joined Van Halen.
Not only was a future Boston member involved with Hagar, but Sammy toured with Boston for two years (1977-1979) and he opened for many of their shows.
Gary was involved with most of Sammy's solo work between 1977 to 1985. He first appeared on Sammy's 1977 release Musical Chairs. This is also the same album that Sammy's cover of Sittin' On The Dock Of The Bay, with backing vocals by Brad Delp, Barry Goudreau and Sib Hashian (credited as Bos-Tones). Although Gary did not perform on this track.
It's interesting to note that Gary is also did some keyboard playing for Sammy (as well as guitar) on some of the solo albums (like Standing Hampton and Three Lock Box). The last Sammy Hagar album Gary was on was the 1984 release VOA.
You can find out more about Sammy on his official website at www.redrocker.com.