Looking to upgrade. Have wore out husqvarna 54 inch. Replaced one of the transmission units a couple years ago .I think hydrogear 2200. The other is failing. Pulled it of and changed oil. It's limping along (they're supposed to be a non- service part) . Anyway have a minimum 4 acres.hills.trees. looking at Gravely ZT HD 60 inch. Anyone have one or similar. Studying various mowers/ brands it looks like the hydrostatic transmission, engine , and mower deck is where the longevity comes from. Question - serviceable(fluid/filter change) transmission 3100 version and above. Have you had good longevity ? Kawasaki engines good results ? Looks like $6000- $9000 approx prices. (Obviously there are higher dollar machines). One other thing . Will probably add pull behind leaf vacuum for fall. Thanks. Would rather be fishing!