Help finding leak

I'll ask in a more clear fashion: How can I determine where the leak is coming from?

I can re-create the leak by turning on the engine. The problem is I can't see that far into the engine. I imagine I won't be able to see the freeze plug between the engine and transmission when its leaking. But is there a way I can eliminate other leaks, like the intake manifold? It doesn't sound like much fun if I have to pull the engine for the freeze plug.

It appears to be leaking from between the engine and the transmission, but I also see quit a bit of moisture where the intake manifold sits on the head, although I don't see the leak itself.

Background: I've been plagued with coolant problems for the last 6 months or more. I've replaced the radiator and have been adding a lot of coolant. The engine wasn't leaking on the ground or driveway but I had to ad coolant. I've also changed the thermostat. 3 weeks ago I finally gave in and added Barrs Stop Leaks.

I found a small puddle of coolant underneath the intake hose (that goes to the filter) that I couldn't see until I removed it. I attempted to make the leak happen again, but for some reason (maybe cold tonight) it didn't leak. I'm going to head to Autozone tomorrow to use their pressure tester to see if I can see where the leak is coming from. I'll try tightening the bolts if I still can't find it with pressure.

Sure enough, added pressure, found the leaks all around the intake manifold. I replaced all of the upper gaskets. I'm almost done with the project, but having one final problem. I have one left over terminal where I can't find the port. I have attached an image of the terminal. The wire is black/yellow.