Gordon & Smith "Modern Machine" - I have 2, wondering when they stopped making them?

At the beginning of summer I bought this board, not knowing anything about it.  Turns out I've really enjoyed it, and decided it is great choice for surfing some of the slower breaks that people like to longboard even when the surf gets big.  It has lots of foam, and little drag with the single fin, so I can get into waves nearly as well as I can with my 9' board, which make me competitive with the longboards.  

Because I like this board so much, when I came across another one last weekend at a garage sale, I bought it.  It has a coffee colored resin tint on the bottom, and a creme colored tint on the top, with a red pinline and the bow tie logo.  It needs a few repairs, but overall it isn't in too bad of shape.  

Anyhow, it has absolutely no writing on it whatsoever, and I'm wondering when it might have been made.  It has a standard FU box, and a regular leash cup.  My other Modern Machine has a hole drilled through the fin box.  

I know they introduced this model in 1974, but can't find any information about when they stopped making them.  I did see that they did a reissue of this model a few years ago.  Anyone have any idea when production ended on this model?