This SD-1 is from early 1982 so it is a pretty early model. The "Made in Japan" sticker on the label was only used during a short time so it can be used to date the pedal reliably.
The first SD-1s were made early 1981 so this one is fro the second year of production. The most collectable SD-1s are the earliest pedals with silver thumb screw and ink stamped serial number. After those, we have the black label/black screw pedals that was made up until 1988 when production was moved to Taiwan. Since the SD-1 is still in production today and availablity is plentiful, prices have remained relatively low. Although it's an old pedal it's not very valuable compared to pedals like the SP-1 or VB-2.