The numbers you listed are the EPA registration numbers which don't mean anything to anybody other than them, and I am not even sure they could tell you what they mean. Now on to the model number, There should be a 2 by 3 inch sticker under the seat with a model and serial number on it. the engine will have the model type and code stamped into the valve cover or on a flap over the the muffler, or stamped into a piece of sheet metal surrounding the cylinder if a Briggs. There should be a model and specification number on the blower housing, or some models will have it stamped into to the back of the block if Kohler. The MTD engine will have a sticker low on the side of the engine block.
With further checking it appears you have the MTD 4P90JUC engine. Most parts will not be available aftermarket, mainly due to being newer parts. The good news is any Yardman,Yardmachine, Troybilt, or Cub Cadet dealer should be able to get any parts that you need. They are using a 3-1 blade, it is designed for side discharge, bagging, or mulching.