It was the Yamaha GX-1. From 1973. And it does not look like a fridge!
One of the keyboards had side to side motion for vibrato.
The Yamaha EX-42 organ (1970), the predecessor of the GX-1, also had velocity-sensitivity and,
like the GX-1, the solo keyboard could sense side to side to side motion for vibrato.
Regarding the GX-1, afaik it first appeared in late 1974 and was first shown outside Japan in early 1975.
Here's a video of some guy demonstrating an EX-42:
This was film composer Lalo Schifrin's favorite organ, and it can be heard on scores such as The HellstromChronicle (1971), Dirty Harry (1971), Magnum Force (1973
) and Enter the dragon (1973).
"The (Yamaha) CS-80 is a step ahead in keyboard control, and a generation behind in digital control" -- Dan Wyman, Jan 1979