That's funny, my doctor has been telling me that for years!
I was a tech too, and I was the same way. I keep my jeep pretty clean and was very proud of the fact that it didn't leak (as I hear of so many that do). We could both see where it was wet from the leak had made the metal a different color verses the other areas that didn't get touched by the leak, but he said he can't find it since there is nothing left to trace. He said it may be the rear main, but didn't want to just throw parts at it (there was a little seepage from there but not enough to cause the amount I saw). So he said I could leave it there for a few days and see if it leaks again.