I believe the blue stripers were made in 1975-76 and were the last of the Grayling SK's. They are just as good as any made then and since. The grip is great and the speed is impressive.
We have some "experts" that visit here who can determine exact year with a bit more info...such as overlays description on back of riser or even tip color, etc.
My understanding is the '75 blue striper had white as one of the colors on the riser overlay while the '76 was gray and blue on back of the riser.