How reliable...Purchased John Deere x340 in 2006. At 200 hours K58 transmission needed replaced. Last week (June 19th,2012) replacement K58 transmission died. JD replaced original transmission at 200 hours at no charge even though I had just passed warranty period. I am now at 585 hours when the second one went. I am in discussion with my JD dealer and it sounds like they will be helpful with this 2nd transmission. My main issue is what replacement transmission to get. My research shows numerous problems with the K58 not being able to handle ground contact and hilly environments. I purchased this x340 from JD dealer for $5000 in 2006, because I knew the box store units were not of the same quality so I was willing to go the extra expense for a machine I thought would last me 20 years. The transmission problem in the x300 series involving the durability of the K58 is very evident in many garden tractor blogs, and hopefully JD will resolve this issue. I must say overall the x340 is excellent and my dealer has been very understanding and helpful with my problem. JD realizes the issue with the K58 because they sometimes issue financial assistance with the problem by dealer paying 1/3, JD 1/3, owner 1/3. Average cost of K58 replacement is $1400. My question is should I go to the Tough Torque K66 instead of the replacement K58 which will probably fail again. I mow an acre lot, mostly level, and snow plow a 50 yard driveway. I'm suspecting the snow plowing is too much ground contact for the K58 and I believe JD realizes the weakness of this transmission for this level of garden tractor. I would appreciate any comments or advice because I will be resolving this issue with John Deere this week. I am retired and really can't afford any expense for this. Thanks, John