This Module is currently available.
Octal AD / AR Expander for Octal VCA and/or V-Gates
Why not add eight (8) AD / AR Envelope Generators to your system – All in 2 MU ?
It interconnects with our famous 1510 Octal VCA and our incredible 1610 V-Gates (modified). The SSL “V-Bus” ribbon connector standard makes this possible with the simplest connections. The V-Bus ribbon connects to the rear of some SSL modules and allows easy access and CV normalization between V-Bus enabled modules.
The 1515 Expander module connects to the 1510 VCA module and is required in normal use. The 1610 V-Gates module is NOT required but is compatible with the V-Bus standard and a recommended addition to every synthesist’s system.
https://steamsynth.com/shop/moog-unit-modules/ad-ar-expander-model-1515/
These merchants probably sell this module. Huh?