Is the hoe a John Deere original, or aftermarket? These were not rare, or uncommon. I think they were at their best with clam bucket. A local died this weekend, he'd had one thirty years. A very nice unit. Check the front crossmember. If the bolts attaching it to the track frame failed, the lazy solution was to weld it. This didn't allow the small amount of movement necessary. The crossmember would break, putting tremendous strain on the transmission housing as it cantilevered the front of the machine. Broken transmission cases were the result. Last year I looked at a 450C Dozer, agreed on a price, drove it a bit. I arranged transportation, and a friend went with me to haul it. He was much more knowledgeable than I. We ran it quite a while, the seller was visibly agitated. It began to smoke from under the rear. I searched out the source of smoke; a rubber hose. It ran through the belly, and connected to the engine breather. In this process, I noticed the transmission housing had lots of fresh yellow paint, and welded on patches. I didn't buy it.
Willie