I remember first reading it in Kerrang or Metal Hammer around the time "Vulgar" came out and it was in an interview with either Dimebag or Vinne Paul. Can't say 100% sure if it was either of them that mentioned it in the interview or if the journalist just chucked it in as part of the article. Apparently the track he is on is "In Over My Head". It came out in 1984. I also remember reading a few reviews of the album over the years saying David Bryan was on it...tried to google it just then and couldn't see anything other than him being rumoured to have appeared.

I do have the CD, but it was a re-release that doubled up their "Metal Magic" release with "Projects", and the only album credits on the CD is for the Metal Magic album.

So...I am pretty sure but don't have the definitive proof for ya, Mr Son