The leak is probably the "O" ring in the electrical connector. The transmission fluid is Shell 3403 which you may find at a Shell Distributor or you can stop at any Mercedes dealer or possibly at a Chrysler dealer and buy it. It is a unique ATF so don't put just anything in it. There is no dipstick because the level is critical and, in addition to the dipstick tool, something is needed to measure the trans temperature when you fill it. I use an infrared thermometer that I aim at the oil pan but the dealers, I was told, plug the car into their computer and it tells them the temp. I don't recommend fooling with the transmission unless you have a lot of extra cash to cover your errors!