The 440P merely reflects the recommended fuel, and all 440's were premium fuel engines that year. .It has no bearing on being an HP engine,since all the 440's then had the same compression. D440 refers to the year of the car. Both 68's' I own are stamped HP, and have the VIN on the block and transmission, Built in the fall of 67'. At the very least, the top pad on your engine would have been stamped HP. Prior to a VIN# stamped, you need the top pad stamped HP, and the date on the pad should be very close to the build date on your fender tag, like the 67's. if the engine is 10-30, then the date code on the tag usually is right after that, up to a month I've seen.(67) Look on your tag. if you have a 401 through 430, your car is six months newer then the engine. My 68' is stamped HP,and is dated 10-10, and the date on the fender tag says A13(oct 13)