I checked under my dash and found no similar connectors. Mine is a 2000 though so I'm sure the harness has some differences. It looks almost exactly like the TC connector which doesn't help since again, yours is pre-1999. I'll check again when I have time.
pretty sure its not radio related. The only other thing I can think of that might be up in that area is the light for the glove box but I thought it was just a 2 pin harness