Another BTW -- Officially, according to the 1978 Pearl (US) catalog, these are called "Vari-Pitch Cannons." They offered a double-bass set (Model F-8DVP and Model FW-8DVP) that had (along with 2-14x22 BDs) 5 of them plus a Vari-Pitch SD. Also offered was a single BD set-up (Models F-6VP and FW-6VP).
On page 11 of the same catalog, listed are 10", 12", 14", and 16" diameter vari-pitch drums (on double concert tom stands, although in the "set" versions the 16" is a "floor tom" with legs), and they ARE listed as being "PHENOLIC" shells (so I was wrong in my first post -- just going by my sometimes faulty memory there -- and anyone my age understands that!).
Man, those old catalogs really are important to have access to, huh?:)
Craig, I'm needing to go to work (and you're probably not up yet), but I may be calling you this afternoon...
Bill