Visually detecting a rear main seal leak?How?

Gear oil in an A833 will stink unlike ening oil. Pull the inspection cover and see if it's flinging off the crank (you'll see little dark fingers of semi-dried oil and dust). If it is, good sign it's the seal and not the pan. You can also use a flourescing dye if you can find a buddy with the setp, or pay a shop... You'll still need the inspection cover off...