Seems like there's gotta be some sort of logic in the model numbering system for Lawn Boy mowers. For instance, model numbers after the 8FH13LB style start with a 3, 5, 6, 7 or 8. Seems like the ones that start with 6 are commercial F-engine mowers, non SP. And the ones that begin with 8 are commercial F-engine SP mowers. The ones that start with 7 seem to be 21 inch decks, but deciiding what engine goes on them must be another digit. The ones that start with 10 are obviously, like my 10247. Are they 21 inch steel decks and a later digit says what engine? 22 series appear to be the commercial units like the 22260. Is there like a legend or something available that splains the model numbers?