After years of getting by on my gimpy L120 that I posted about three years ago I've bought a JD X320 for my two acres of lawn. I had decided to get a X500 though I really didn't want to spend that much money on a mower. The JD dealer talked me out of spending that much and assured me that the X320 was stout enough for the 2 acres I mow, even after I told him it was quite hilly. I know the 320 has the K58 transmission, and the 500 has the K72. Here's the link to a thread I posted about the L120 back in '07:

http://forums2.gardenweb.com/forums/load/tractor/msg0716070624265.html

Initial results with the 320 are encouraging and it is a pleasure to operate, but I want to know if the K58 will hold up to my lawn. I am only mowing with this machine, nothing else, e.g. no plowing, grading, or hauling.