I am trying to get some facts on the Deere transmissions used in the above series, the JD site states that in the 300 series the Tuff Torque K58B is used but I am unable to find any specific info on the X500 series other than that in the upper models the drive has a replaceable internal filter, can anyone identify the drives used in the 500 series and is anyone able to confirm that the K58 is used throughout the 300 line ? thnks in advance to all that can help/reply.