Guus: It means your engine was assembled on the 15th of February. The nagging question has always been if my car is a 1965 then one would assume that the engine is a '65 also and was built on the 15th of February in 1965! That is assuming it is the original engine! By the way........Happy Birthday to your engine this Sunday!!!!!!! Bill "Swamp Rat" Hadley Baton Rouge, LA