I am looking at an X534 tractor on e-bay and the seller says the unit has 350 hrs on a 2006 tractor. I am moving up from a 1976 317 that I had bought new then and I only have about 450 hrs on it 36 years!!! I notice that a lot of tractors of that vintage have as many hours. Am I needlessly worrying? They must have really big lawns!!!!