ORIGINAL: rcdude7
OS has been making .40 size engines for the last 44 years, some are quite valuable and others not. The value of your engine cannot be determined without more info.
Try this and see if you can find your engine.
http://www.osengines.com/history/ostimeline01.html
[8D]I'm trying to determine the value of this engine for someone else. This
person bought the engine 5-6 years ago with thoughts of getting into the
hobby, but never did. I'm now trying to get more specific info.