I appreciate you so much and yes I'm on the Yamaha Facebook pages and have gotten some info but no one has one and I've also called a few drum shops to which they've taken my info and then never called me back.
I've seen those for sale a couple times the past 2 yrs....because I've been looking at all the concert tom hardware of that era. These are the 900 series mounts and Yamaha made them for top of the line concert tom kits. Most of them now sit atop working concert tom stands. Finding just that mount by itself is very hard. You don't see many Yamaha concert tom kits in the late 70's through 80's. And the reason for that was most everyone bought mostly Tama, Ludwig, Slingerland.....along with a few Rogers, and Pearls. You rarely see the Yamaha's (or Gretsch) in concert tom configuration. Those 2 companies were selling lots of high end standard tom kits in that era.