well as far as reliability they are very good in that department, really only thing you have to worry about is fuel, air and the glow plugs functioning properly. i just worked on one today that wasnt charging the battery and it just needed a simple 80dollar part compared to an 04 model year which would prolly take a 500dollar part haha. try to get between 100k to 150k if you have to get a high mileage one, they are out there. my buddy that i work with has over 300k on his car and there is a car out there with over 1million miles on it that has never had the motor rebuilt or replaced so they will last. as far as ease to work on they can be a pain sometimes, depending on the problem. sometimes parts can be hard to come by for the really old ones but the late 70s and early 80s aren't a problem. just make sure to ask when the glow plugs were replaced, if its had any motor work done recently, and maybe take it to your local shop and have them do a 22 point inspection on it. you could be buying a great car or you could be buying a turd that will cost more to get fixed than you payed for it. that small fee for the inspection can be well worth it. ohh and make sure it has the electrical plug(comes out the bottom by the front bumper) for the block heater, and use it in the winter to help with cold starts if you do choose to buy one. wheewwww lemme know if you got any more questions i can answer for ya!