Hi everyone , I´m thinking of buying a 4420. was wondering what the parts availability is like in the states , main reason I´m thinking of buying it is because, we already have a 7720, but the terrain is usually wet and very soft at the start of our harvest season for corn , so I figure the 4420 is a flyweight next to the 7720 and hence I should have fewer problems with the gettin stuck and all. What do you all think .