from what I have read the 533 replaced the 431, they look very different, they changed alot on the 500 series, they also have a warranty that is as good or better than a deere. if I could of found a half way decent deere dealer I would of looked at one, but the ones in my area, have really poor service, and sell their stuff higher than list. I am not going to pay higher than list for one. we found a great MF dealer, and he gave us a great price, an sells implements at cost when you buy a tractor from him. I looked at kubota, and new holland, and although the dealer was good, they did not offer the HP I was looking for, for $ I could afford.