The Gibson RD Custom was an active instrument, like the RD Artist, and whilst it did feature the Artist's bright mode, it did not have the additional expansion/contraction circuitry. Controls are somewhat similar to the RD Artist, and quite different from the traditional Gibson four-pot layout. There are two volume controls, one for each pickup (though not the two you'd expect if you're more used to an SG or Les Paul - or indeed the passive RD Standard) numbered 0-10, and a master bass and treble control - both numbered 5-0-5. These add or remove treble/bass from a neutral central position, rather than just reduce treble as is the case with a standard tone control. The switches are a three-way pickup selector, and bright-mode on/off switch.
The above sheet was circulated by Gibson in 1978 - compare with the equivalent sheet for the RD Artist.
Need the value of your guitar? The Official Vintage Guitar Magazine Price Guide 2023 is out now