12V switched Pin on the ECU?

Does anyone know which ECU pin would be a good source for 12V switched (must not appear at the accessory key position)??

ST165,+B1, EFI Main Relay Pin52?
ST185 [early] +B1, EFI Main Relay Pin71?

What are you trying to power. Most circuits are relay controlled to minimize amp draw on the ecu.

You're thinking about it backwards.
The ecu doesn't send 12v out on those pins. Instead, the ecu consumes 12v on those pins.
So what you need to do is look at your wiring diagrams for your chassis (assuming it's still in a factory state) and pick a 12v circuit to splice off of that has room to power what you are wanting to run. The better/best method is to run a new relay and set up a new circuit so you're not overtaxing what's currently in use.