The Gibson GK-55 was made in 1979 and sold through 1980.  A one year stretch which turned out to be a more sought  after guitar than imagined.  Gibson only made 1,000 of these guitars and many have been trashed over the years.  We have no idea how many of them are left or who has the original one I bought back then that was stolen.  Just like the Musican amplifiers were that of great quality, these two influential items were taken out of production.  I know the Music Man amplifier vanished because of the high manufacturing cost.  Can't beat the quality.  I still have a Music Man today totally revamped and sounding great.