Ive been using those rear engine snapper mowers all my life. I have never used any other type to mow my own grass or parents grass. My current one is a 15/33 with a 15.5 Kohler and it's 10 years old. I use it once a week to mow and Acre+ for 9 months of the year. It still has the original deck belt. I have replace the wheels and tires, batteries and drive disc. Thats it. My last one was 22 years old with a 11 hp Briggs (11/33) with the handlebars and when I bought my new one I gave the old one to one of my sons who uses it at home and a little for side jobs. Still going strong. The one before that was one I use to mow or grass with as a young boy. I'm 57 now. They are still built as well as always (just the rear engines) I would venture to say the one you have pictured is somewhere between 1997-2007. Even if you spent 400 on a new engine you would have a great machine.
Here is mine that I use now, almost 11 years old. Still kickin it like day 1
