You are right, having spares to equipment that I use is a silly thing and I should sell it all. I dont use the S1686 because I'm currently using an asus p65up5, for a gaming system. And to be fair, you are asking for a VERY rare and special part. Items are worth what people will pay for them. for example, I'd practically sell one of my kidneys for a working asus p65up8 with the pentium pro daughter card! The "common" slot 1/socket 370 adapters run the gambit for $5 to $30. But if you have ever used one, the $30 ones actually work while the cheap ones are plagued with issues.
I'm still willing to accept an offer, but keep in mind, I bought the only pair I've EVER seen on eBay. And I paid $25 each for them.