This thread is intended to be a crash course on the revvy as info has been rather scarce (I started playing after the Rotor was released, sue me). Please post corrections or things you'd like to add to it, I'll be editing it as we go along. This is what I've got so far:
All revvy parts fit all revvy shells regardless of age or model. Mix n' match.
Early (Viewloader) revvy shells were tough, kinda soft feeling. Came with opaque, tupperware-esque lids. Indestructible.
Later (JT) revvy shells were harder, much more brittle plastic, often translucent. Came with clear, very fragile lids.
New JT revvys use a shell material very similar to the originals but still have the fragile clear plastic lids.
9 volt: Single 9v and an eye in the feedneck. Fed approx 9bps.
12 volt: Dual 9v and an eye in the feedneck. Fed approx 12bps.
xboard: Dual 9v with a sound sensor. Fed approx 12bps, but more consistent due to faster response of sensor.
All revvys used the same motor?
Early revvys used a rigid two prong paddle. Later ones used a flexible four prong model which fed a bit faster. Six prong aftermarket paddles were available that fed even better. The new JT Revvys use a spring loaded four prong model which supposedly helps keep the thing from jamming.