the MF 35 with the perkins engine is a great tractor. Look at the overall appearance , check how easy it starts, check the 3 pt. hitch for shaking or quivering when it is raised, check for loose main shifter gearstick (these have a tendancy to cross gears between 2nd and reverse but mostly due to operator trying to be to quick but are easily uncrossed by removing transmission fill plug a moving the shifter rail) check for leaks. The rear oil pan seal is quite common to leak with age but is very easy fixed, also pto seal in older ones will leak, also an easy fix. Generally look as looking at any other machine. They also have an indirect injection engine and will require you to use the pre-heater at colder tempatures. Also the air cleaner is an oil bath so take the canister off of it and look to see if has been serviced properly. My Grandfather bought one new in 1961, my Dad had it and now I have it, 10,000 hrs. and still going strong, over the years we have added things like spin-on oil filter and dry type air filter and power steering and an alternator. Still use it about 200 hrs. per year tedding and raking hay along with other chores. Probably got more life in it now than a new compact.