Keyboardists - what's being used on "No Silver Bird"

A lot of the sound on that track is Norman Petty treating the keyboard afterward with various effects - tape delay and use of the famous 7th Street Studio echo chamber, plus eq and compression. But some of it probably is the “Sugar Shack” Solovox keyboard
 
The Solovox would have been an antiquated instrument even in 1968. The keyboardist in the group talks about Petty acquiring a brand-new toy, for making string sounds. But yeah, Petty was a wizard at sound effects and treatments.
 
Possibly an Ondioline? They were in widespread use in '68 (Blues Project). A Solovox was used by the Four O'Clock Balloon (Northland Battle of the Bands) - Sounds way too "monochromatic" for the sound on NSB.

Solovox in action. The band overwhelmed the studios recording equipment which caused the distortion http://www.youtube.com/watch?v=q8-ehnutcoo