I just replaced my starter in my 1977 450 SL. The top bolt isn't easy but not all that hard. I removed the Transmition dip stick tube from the transmission. It runs in front of the bolt. Use a extra long extension with a 19 mm swival socket. feed the socket along the side of the transmission to the bolt. It comes out fairly easy. With the Dip stick tube removed you can just reach your hand in to re-start the bolt after the new starter is in place.