This interesting image shows Robert Moog working on the RD-77, and is taken from the 1978 Norlin Artists Perspectives flyer, and came with the accompanying text...
The 'second generation' RD referred to in the text became the RD-79 when launched. The phrase 'Arr Dee Too', also has resonances with R2D2 - the impact of Star Wars was taking the world by storm; at the time the RD basses were themselves pretty futuristic!
One very interesting feature of the guitar he is working on is the bolt-on neck. Was this just the simplest way to create a test instrument, or something that was actually considered for the RD? According to one member of the design team, Chuck Burge, the RD series was initially planned to have a bolt-on neck, and idea dropped before the bass went into production. Furthermore, at least one potential prototype RD has surfaced with a bolt-on neck - here. Although the text suggests the instrument in question is a bass, the shape of the cavity, as difficult as it is to see, may suggest a six string guitar.
Gibson RD bass guitars for sale
1980 Gibson RD Artist Bass Sunburst
Antioch, Tennessee, 370**, UNITED STATES OF AMERICA
$3999