I have a 1982 F340 engine from a Lawnboy Scamp model 8603 20" self propelled mower. I also have a 1994 Lawnboy Gold Series model 10520 21" self propelled with an F series engine. What I want to know is are the engines on these two mowers the same? The only difference I can see is that the older mowers carburetor is plastic. Any information from you readers is most appreciated!!!!