been on the look out for a used 40ish hp tractor and have narrowed the field to a ford or MF. supposed to go look at a massey 135 diesel next week. was told about it by a guy who knows the seller so didn't get many details but he said it was real clean. not sure on year, probably late 60's. are there any red flags i should look for on this tractor? how many hours would be considered high? i know a MF 135 is a good tractor just wandering what to look for.