Does your Bell Housing have an inspection plate on it? Mine does and in the bottom it has a small hole about the size of a match stem that goes back into the inside. If I find an
oil drop I can tell if it came from the inside or the outside of the plate as the wind will blow a small amount of
oil all over. What I do to make sure is wipe it clean and then stick a small piece of cotton in the hole. Later I pull the cotton and if it is oily on the part that went inside or
oil comes out I know it is inside the plate and not coming from above. Since the inspection plate only has 4 bolts it is easy to remove and lok to see what is going on. And I also check the pan bolts regulary as they seem to tend to want to loosen some. Only found one leak at a valve cover.
Ron