Ken, I thought the same thing as well. I went in the warehouse and looked at 400D, E, G and H cards. Only ITT's 400E had anything physically connected to pins 3 and 18. San/Bar's cards also use pins 3 and 18 for music source input.
Using the other cards requires a completely different wiring/arrangement. Since the original poster has indicated that he's not familiar with the system, I sure don't think that an upgrade to the Western Electric wiring will be possible. We are going to need a true plug and play card in this situation for sure.
