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Update: See the comments of this post for more info on the EX-42. It's not a GX-1.
However: according to the
list of Yamaha products on Wikipedia: "EX-42 (1970–1977, stage model, design origin of GX-1)"
"Yamaha Electone EX-42 Vintage Analog Synthesizer Organ Keyboard
with two (2) original Yamaha R-60B rotating tone cabinets (KILLS LESLIES!)
For your consideration is a Yamaha EX-42. This polyphonic analog synthesizer is one of the rarest, most complex, and most expensive synthesizers ever built. Yamaha's flagship synthesizer/organ precursor to the ultra rare Yamaha GX-1, this beautiful instrument packs all the sonic possibilities of a standard organ and polyphonic synthesizer into one gigantic and unique package. When released in 1970, the EX-42 had a $32,000 price tag. That's $182,000 today when adjusted for inflation, making it the second most expensive synth (in today's dollars) that Yamaha ever made. It is rumored that less than 200 were built. Don't miss your chance to get this extremely rare and incredible-sounding synthesizer for much, much less!

Even better, this listing includes the two extremely rare (2) Yamaha R-60B tone cabinets that originally came with this unit. You can see one Yamaha R-60B on the right side of the second picture and two in the third picture. The Yamaha R-60B kills any Leslie! It has three (3) vertically rotating speakers that are switchable on/off at the players option. The soundfields that this 200W tone cabinet creates are absolutely unreal.

This synth is in great condition. All the knobs and sliders that we have tested work perfectly, though we have not tested all of the functions on this synthesizer. Thus, it is sold as-is.
This auction also includes the synthesizer and bass pedals, but the matching bench is not included, as the owner prior to the previous owner wanted to keep it.
The features of this synthesizer are much too extensive to list here. There are a few videos on YouTube that fully detail all of the capabilities of the EX-42. Just search for "Yamaha EX-42" and prepare to be amazed. Make sure to look for the R-60B in action too!

This is a very large instrument - 45" high x 60" wide x 32" deep and nearly 500 lbs! - and can only be shipped via freight. The $590 shipping cost is just an estimate. Within the Continental U.S., transportation costs (freight or mover) will vary depending on proximity to Los Angeles, and typically takes more than one week to schedule and deliver. International shipments will be considerably more expensive and will take around two weeks to schedule and deliver..."
Update via Z in the comments: "The photo of the EX-42 in the crate was stolen from my Photobucket page. I took that photo 2 years ago when I sold a EX-42
http://s187.photobucket.com/albums/x30/zudio/For%20Sale/?action=view¤t=DSC_9036.jpg"