This 8HP module contains 3 VCAs and a fuzz/distortion. The VCAs are similar to the ones used in the NLC Cluster; simple OTA based but work very well.
The fuzz/distortion is part of the bottom VCA and is a typical diode based affair, on the PCB the space for these are thru-hole so you can install Si or Ge diodes or LEDs. Turn the Fuzz pot to 0 if you just want VCA.