Found this when hunting, and thought it was a little odd. It has the serial number in the battery compartment, but clearly says made in Taiwan. The decoder dates it to 1981 though. Just thought I'd put up a post incase anyone was interested. I don't look too much into serial numbers and that, so I don't even know if it's that odd.
It is a bit odd but it's not from 1981 as the serial number decoder suggests. These serial numbers were used on the first Taiwan pedals, probably around mid 1988. So far I've seen these serial numbers on DS-1, HM-2 and SD-1s but there could be others too.
Yeah, I read the page on the SD-1 and production didn't move till 1988 or something, so I figured it would be from around then. Just thought you might want the serial number for your data.