That's a possibility I'd considered, but the Gillette guide at Safetyrazors.net indicates that production of the SS stopped around 1974 - but they qualify that with some ???s so that's probably it. Maybe made overseas for local consumption.
D1 is my birth quarter so I'm doing some homework to see if I really want to acquire a set of D1 Gillettes.
The razor pictures is from the '80's, and if it is D-1, then it is from the first quarter of 1983 (Jan-Feb-Mar) production. That style of SuperSpeed was made until around '86 or '87. I have an identical razor, an F-1 from 1985. Very nice razors, though a bit mild.
(Wow in the time it took me to type this, pictures and more info had been provided, I have slow fingers.)