Hey Doug,
That Zenith is an amazing find. I think there must be a fair amount of undiscovered "new" old tv related stuff lurking in attics, old tv shops and wharehouses. Forum member Steve Hoffman's '64, never turned, on Packard-Bell color roundie comes to mind. I came across a 1960 RCA WR-64A color bar generator new in the box in 2003. It had been shipped to a video supply dealer in So. Dakota and never opened. I won it on e-bay for $9.95.It can be seen (hopefully) here:
http://community-2.webtv.net/StevesCT-100/doc/
-Steve D.