I have a 1992 300SD with 102K that I should be picking up today that will have a rebuilt long block. I think the long block is the way to go..if nothing else for the 48/50 warranty instead of the 12 month on the short. As for warranty from MB...I think they will help you out if your car has less than 75K or so. They offered no help to me nor another gentleman in town that had about 125K on his car. The dealer did however seel him the part at cost because they had sold him the car and he had been a customer for about 15 years....Good luck