YouTube via delshannonnetwork.
Inspired by this excellent post: Synth pop, circa 1961 on Sequence 15.
"Del Shannon singing "Runaway" which was a #1 hit in 1961. This became Del's first big smash and catapulted him to superstar status in over 21 countries. Max Crook was his organ player, playing a "musitron" which was built from parts from a clavioline, Viking 85 reel to reel machine, Fisher K-10 Reverb Spacexpander, a Gibson guitar amp, and several other parts and pieces. Maximilian's musitron was the perfect compliment to Del's soaring vocals and seering falsetto."
Update via Stephen:
Del Shannon Runaway live 1982
Re- Published on Aug 30, 2009 hastronder
Sequential Circuits Prophet-5 Rev 2 takes over the lead.
Del Shannon Runaway Live David Letterman 1986
YouTube via DelRocksMySpace.

Paul Schaffer on Oberheim OB-Xa. The audio isn't too good on this one, but it is fun to watch. Update: image of Max Crook via his website.
I'm guessing that's the "musitron" Clavioline.