1983 Chevy Truck Leaking Tranny

Hi all I have a 83 El Camino with a 229 v6 and a 350 tranny and it recently started leaking quite badly. I narrowed the leak down to the passenger side at the pan, between the gasket and tranny housing. I replaced the filter, gasket etc. And the leak was still there in the same spot, thinking maybe I overtightened the bolts or something, I R&R the pan & gasket again and the leak was still there. Lastly I bought a new pan and installed with a new gasket plus ATV silicone sealant installed it finger tight plus a 1/4 turn on the wrench, waited 3 hours before installing the new fluid and I just took it for a drive and it is still leaking from the same region. I talked with a friend who used to be a mechanic and he said it might be the modulator valve is stuck and needs replacing and thus the tranny has to much pressure but he was not sure. Note: there is a 2 wire connector that is hanging down on the passenger side of the tranny and I could not figure where it plugs in, I don't know if this is supposed to be connected to the tranny or related at all.