We picked ourselves up a 544a Yes it is a little older, but it sure has been a rock solid machine. Pushing brush up, cleaning corals, ect. No complaints so far. John dear has been good to deal with for getting parts. A neighbour has a 644c, uses it for cleaning his drive in the winter. He has had no problems with it so far. Sorry I am no more help but I need to make a few posts in order to ask a few questions about my 544a.
Ranchingelec