The 'S' is approximately a 1944 model. It was a one owner with only one set of new tires which have been replaced on the rear. The tractor had very little usage and was in dry storage for several years. The 'D' Case is about a 1950 model and was also a one owner with one set of new rear tires. It had been stored in a warehouse for about 20 years, had very low field hours and is almost like new in every way.