Follow-Up - found one!
Just to close out this thread, I did consider the little units linked above, but I was loathe to spend $54 for something that could be sold in a dollar store if found in sufficient quantities. In looking through web sites, I hapened on Tru Trak, where I was reminded that the large version of the Pictorial Pilot actually has a slip/skid ball incorporated in the face (my smaller version doesn't).
"Hmmmm....since they manufacture their autopilots, I bet they have a supplier for those little balls!" I found myself thinking, so, figuring that if I could get my hands on the sub-assembly, I could build the mount that I needed. So I fired off an email to Tru Trak, asking if I could possibly purchase just the little ball in the tube.
Next thing I new, I got an email reply that they had shipped me a "miscellaneous part" by regular mail, and sure enough, when I got back from Moscow, there was a little envelope with exactlywhat I needed - and it was already in a mounting sleeve with ears for screws that fit perfectly under my EFIS. I'll have to post a picture.
Cost? I have no idea, because they didn't charge me for it! I almost hated to post this, cause I'd hate to start a "run" on their good will.... but I can assure you that when I go to add altitude hold to my system, I'll be buying Tru trak (again!).... What great customer service!
Paul Dye