I have an '82 300SD with about 90,000 miles. The transmission sometimes slips between gears with a slight rpm surge. Also, when I put it in gear (especially into reverse) I sometimes get a 3-7 sec. delay before gear engages. When I shift manually, it is fine. Transmission fluid is good and at appropriate level.
Does this sound like a vacuum pump issue or a bad transmission? Or something else? Thanks in advance, Joel