I posted initially in the Bike Mechanics forum, but didin't get many leads there....

I rescued a Suntour Superbe Pro rear derailleur about to be tossed The owner lost some parts that I thought I have in my parts box. I had the pulleys and washers, but I'm still short one item.

The Rear is missing a recessed hex nut for the upper pulley. It resembles a small brake caliper's mounting bolt.
It's appearance is like the lower pulley's fastener, except the lower pulley fastener is a BOLT.

I know Suntour released a couple versions, with different cages, pulleys, and adjustment screw placement.
I have the closed upper cage with the stud. (see pic)

I tried Loose Screws, Yellow Jersey.org, but no luck.
Does anyone possibly have this nut in their spare parts pile?