I was looking at a PH-1r on Ebay today and the seller was talking about how it was an early edition of it, and I was think, "if it's early where is the silver screw?"
But it occured to me that I've never seen the PH-1r (specifically the R model) with a silver screw, I have seen the PH-1's with them.
So I figured I'd list all the pedals that I have seen with silver screws, and we could get a consesus of which ones do have them.
I have never seen an SD-1 with silver screw though and as with DM-2 and sighted silver screws, they must be really rare among all the models that were released in 1980-81 during the transitionperiod.
Pedals with s/n 0400 exist with both SS and BS. I have for example a PH-1 with SS with that s/n and a DS-1 with the same s/n with a BS. I have also seen an OD-1 with the same s/n which had a BS.
The screw change happened around the time they started using 6 digit serial numbers so there may be silvre screw versions of the PH-1r and SD-1 (which was released after the PH-1r). The next pedals released was the DM-2, GE-7 and CS-2. These sometimes also pop up with silver screws but I doubt they're genuine.