I'm going to be selling my John Deere 657 mower here soon and I'm not sure what it's worth. Any thoughts would be appreciated. It's either a 04' or 05'. The engine was replaced 2 years ago with a 23 hp Briggs & Stratton and now has 40 hours on it and a new muffler was put on when the engine was replaced. It has brand new hydro pumps that were put on this week. The mower is in really good condition and runs great.