WHTrunner

I'm in the middle of doing some extensive touch up painting on my camaro right now, and I looked under it a few minutes ago and found a good sized puddle of transmission fluid under it. It's more towards the front of the transmission, between the engine and the pan.

What would cause a leak like this? I would expect it to be a gasket, of course, but which ones would cause an external leak?

I've never worked on a transmission before. This wouldn't be one of those jobs where I'd have to take out the tranny to work on it, would it?