My 81 300 D has the original engine and transmission. With 402,563 miles it’s far from perfect: no ACC, dead sunroof, dead rear passenger side window, leaks in the rain, and no paint on the roof and hood. But it starts easily, no smoke or overheating – the engine spots a bit but nothing serious and no leaks from the transmission. It still cruises easily at 75 and has good pickup for an NA car.