My John Deere 317 series tractor manufactured in 1980 has been a magnificent piece of equipment. Equipped with the Koeler 17 HP 2-cylinder horizontally opposed engine, it has never let me down. I was surprised to read the "Chris" review on John Deere tractors, where he recommended avoiding 317 tractors because of poor engines. Perhaps that was for those with Onan engines; however, the original air-cooled Koeler engine in my 317 lasted 23 years with one set of rings installed about the 15 year point. It probably would never have needed rings but when I first arrived in CA, I undertook a 10 acre cutting job in over 100 degree heat and did not check the oil while doing so because it had never burned any oil before. The heat thinned the oil so, it burned some oil while cutting, and the resulting low oil level obviously damaged the rings slightly. However, it ran another 12 years before I replaced the rings, and another 8 years after that. Finally, 3 years ago I installed a new Koeler engine that I had bought 3 years earlier for $1400, and stored until I installed it. The last time I checked they were up to $2,000 or so. I'm confident the new engine will run for another 20 years, because I DO check the oil regularly now. Being air cooled, it's also important to change the oil frquently, and a single grade oil is desirable: 30W in average heat and 40W in summer. The 317 tractor is hydraulically driven by a driveshaft from the Koeler engine that turns a hydraulic pump in a transaxle, drives the rear wheels, and supplies hydraulic pressure to all actuators. The hydraulic pump apparently is near indestructible, for I've never had any work done on the hydraulic unit. It just requires an occasional filter change and fresh hydraulic fluid. Belts need replacement when they stretch, and the mower deck drive belt is the one which requires the most frequent change, being the longest. My 317 came with a tiller driven by 2 belts off the rear PTO, a mower deck driven by a long belt from the front PTO (electric clutch operated), and a blade. All attachments are hydraulically raised and lowered. The mower deck is susceptible to rust in the corners by the belt housing and under the belt housing, due to pooling water when wet. The mower deck belt housing covers another long belt that drives three heavy-duty blades, suitable for some serious field cutting. The air-coooled engine draws cooling air from under the tractor. It's therefore best to install a screen under the engine (a piece of 1/8" hardware cloth will do) to keep grass clippings from being lodged in the engine cooling fins. That screen needs to be kept clear of clogged grass at all times. The air is exhausted through the front of the tractor, which is something I never particularly liked, because in dry grass, you drive into the dust and dry grass shavings as you move forward. A dust mask in dry grass cutting is absolutely required, and goggles are preferred also. It's good to have the shop manual (in addition to the owner's manual) for the 317 so you can do most work yourself. Step by step instructions are in the manual for just about any maintenance you desire. Parts are becoming more difficult to find since JD does not manufacture 317 parts anymore. When the new ones are gone, that's it. Parts will then come from older ones that are being parted out. Used parts are OK though, as JD makes hardy stuff. If you're looking for a dependable used garden tractor, look for a 317 that's not been abused. I think some rusty nuts and bolts are of no consequence, nor are paint scratches or slight deck (mower or tractor) rust, BUT you should check the hydraulic unit for high-pitched whines, the engine for smoke or burning-oil smells while running (initial startup smoke is common), activate all equipment to insure the actuators work, and test drive it for proper engagement of the front PTO clutch (no metallic grinding sounds when engaged by the rocker switch)and smooth forward motion. Also when driving, the driveshaft should not vibrate or make any squealing noises from the u-joints. Happy hunting! Robert