Thank-you Bill, That's EXACTLY what I needed to know (one engine has the unit with 312 stamped on it, one has one stamped 369 (and the flyweights look slightly different, but seemed the same weight).... I wondered if I should offer the unit to a member here that needs one (without being sure it exchanged correctly) even though the engine ran with it in.....Apparently the difference is the manufacturer, not actual function or specs..... Thanks again.... Steve