Allow me to shed some light...
I have installed an AOD from TCI into my 67-Vert, it is behind a ~415fwhp 351W. I am installing a custom (universal is the wrong term) wiring harness from Painless Performance too. I have the raw leads that go to the switch which is installed in the tranny but no solid way of connecting them (unless a huge blob of silicone goo counts). So with the plug I can get the connectors on there nice and professional like.