"I bought this second hand for my son who had 4-5 acres of lawn, mainly flat, but it also had a slight slope on parts plus wooded areas. The old single cylinder 17.5HP Craftsman 42-inch mower that came with the property often took him 8 hours to mow this lawn (paddock) because he used to leave the grass to get too long and it needed mowing 2-3 times to get it short again. He was also burning through belts at an alarming rate as the chute was clogged up with cuttings if he mowed too fast. I found this mower locally and the vendor said he had to replace the head gasket because of a water leak/boiling. He had also filled the radiator with gunge to prevent further leaks. Needless to say, he failed to identify the problem! I took off both heads and eventually found a pinprick hole in one head. I sent it off to the local machine shop and they drilled the hole out and fitted a threaded screw. After hand grinding the heads flat on a surface plate, the job was done and it was ready to rock. The amount of power produced from only a 784cc V twin is remarkable. This was the first diesel mower we have had and although John Deere only states that it has 18 horsepower (16 horsepower in the UK!) it can go through 5 inches of grass in one cutting. We found nothing that would stop this machine. The paddock that originally took 5-8 hours is down to 2 1/2 hours now. Admittedly, the deck size was 48-inches, so slightly bigger than the old mower. When the grass is shorter, then it will mow at maximum speed (7 miles per hour) on the flat. The speed had to be lowered on the slopes, as the ground was quite rough. One tank of diesel lasted about 2 mowing sessions. Although we were not looking for a perfectly striped lawn finish on this paddock, the GX355 cut as well as required. Spare parts from the local John Deere dealer were excellent with all the spares been provided from the John Deere central UK depot within a few days. Other reviews suggest this V twin mower vibrates quite a lot, which is not true if you keep it at wide open throttle as it is meant to be operated. I must admit that a set of ear defenders is required for a few hours use as the mower is quite noisy. Another plus point is the ability to grease spindles/steering; a true sign of a professional machine. One dealer I spoke to said the engines often run for 2,500 hours without trouble, so mowers with so called high hours (1,000+) should not be a problem. This John Deere mower is the same size as the 500/700 series and larger than the current 300 series. Everything screams 'commercial mower' quality. I do not know why John Deere stopped manufacturing this mower, but the Yanmar 784cc diesel engine was used until recently. In UK made Countax/JCB/Westwood mowers, oddly enough, they are all now rated at 20 horsepower! If you are looking for a second hand, powerful diesel mower, then try one of these. "