I'm hoping someone can help me as i'm new to this forum. i'm looking at purchasing a Gravely 566 12hp tractor. can anyone tell me what the differences are between a 566 and a 5660? i assume the 5660 is newer, but as far as i can tell they look about the same. any idea around what year(s) they were made? also, about how much is a good condition 566 worth? i've got a lead on one for $800 that comes with a brush hog attachment, has dual wheels on each side, elec start, etc. thanks in advance!