None of the plugs would/will work w/ the factory radio. Everything points to a DCC setup, it's just missing plugs that would mate w/ the DCC. Aren't there 3 different types of AC modules for the s13's? Maybe this could be for the 3rd type that isn't commonly known to most?
The second and third pictures, one side plugs into the chassis harness, then would plug into the factory USDM module. It's pretty much a jumper harness w/ all of the other shit in between...shit that would appear to be for a DCC ordeal. I can provide better pictures if need be.




If I remember correctly, the tape seems to be as if the factory placed it on there, not the average Joe.