i am interested in replacing my Kohler 20HP motor in my 2000 walker MTGHS 48"DECK, the serial number off my walker is s/n 49193 and my spec # off my the motor is CH25S 68543 ? Does this mean it was a 25hp even tho the makings on the machine say 20HP? I would like the most up to date motor that will fit in this machine can you help me. will the kohler 64660 fit and if so will i need to change anything like pulleys or not. the blower is now driven by a regular style "V" belt if that helps. could you please get back to me thanks in advance.