API 7312 1970s microphone preamp (x4) with rack and 2 power supplies

Extremely rare rack of vintage API 7312 microphone preamps that I purchased to be part of my front end for tracking. It is my understanding that these were built specially for one of the major broadcasters and are a standard 312 preamplifier that goes into a VCA volume control and a built in limiter. These look to be complete, but are wholly untested. I purchased the modules and the rack separately, so buyer needs to go through inputs and outputs as well as modules to get it all correct for final use.

API mic pre's are my favorite, so I grabbed these to have a one of a kind rack. I was going to try and trace the schematic and have a tech wire it up with the VCA and whatever limiter controls were on the PCB for a custom 4 channel input rig for my day to day needs and then sell the odds and ends API stuff I am using now. Then I saw a pair of bare 7312 modules in the exact same condition sell for $2000 and realize I have been priced out of my own equipment.

Let me know if you have any questions, glad to help if I can. Thanks for looking!