I have both a problem and a solution all in one to help anyone else that encounters this…
If you have a 1992-1993 3000GT/Stealth (all trim levels, I believe), and you have no audio to the front right speakers, then it may be caused by the removal of the factory cellular phone option.
The wiring for the front right speakers runs all the way back to a connector in the trunk where it can plug into an optional cellular phone hands-free controller unit:
This allows the phone to output audio to the front right speaker for hands-free conversation.
From the factory, one of these connectors has a jumper connector plugged into it to simply complete the circuit between the radio and the front right speakers:
NOTE: That wiring is normally folded up, taped, and tucked up behind the rear strut town when the optional cell phone is not installed.
If your car previously had the cell phone option installed, and then it was removed without replacing the jumper connector, then you have effectively disconnected the front right speaker from your radio.
With the help of Sheridan Engineering, I have been able to source a couple of the correct connectors and have built a couple replicas of the jumper connector:
If you are missing this jumper connector from your car, I can either send you one of my spares (price TBD so that I don’t lose money on parts/shipping), or I can help you get the right connector to build your own. The pictures above should be clear enough for wiring it correctly.
If you caused this problem yourself by removing a cell phone system, then please reach out to me! I’m interested in purchasing some parts related to the factory cell phone option.
I’m still waiting on a reply from Sheridan Engineering on the exact part number of the connector and will post it here when I get it.
!!! I’ve never seen a car phone before. Dude, that’s ghetto. Luxurious in 1991 but today it’s ghetto 
