Well, it didn't last 5 more years. I replaced it this past summer. It was still running but smoking badly. I think, from what I could find out, that it probably had a warped head. It only smoked badly when you were turning.
At any rate, it was a residential mower with around 2600 hours on it. Pretty much worn out. I bought a new one and just recently sold the old Snapper to a retired gentleman who tinkers with and sells used mowers. He got it for $100.00.