This comes from my SS20 test station.  It's been about 10 years since Ive tested one and I cant see keeping this any longer.  Was 100% functional.  Onto eBay now so it can go back to work for someone using the SS20.

You need to install all four to get the SS20 to boot.

I have some other modules loose in my kit.  I will throw these into the box for you to use but I dont remember their condition.