I have been selling weed eater engines to R/Cers on Ebay for awhile now and this type isn't a good seller. When I get to clean out saw and mower shops I take everything and that includes these engines. They are pretty plentiful at yard sales also. At any rate I have quite a few and there are lots of subtle differences in them not only in terms of cc but in transfer port, intake and exhaust placement and size............Bob