I know motors have come up for sale that have been removed from bikes that have been upgraded to aftermarket motors or wrecked (and are in wrecking yards)and people have purchased and installed them and no one is the wiser. Not sure about all States, but when I moved Nevada, the officers at the DMV have an area where they checked the vin on my Harley frame and motor BEFORE I could change my title to Nv. If you want to replace your complete motor, H-D requires the right half of your engine case (with the vin stamping) and then they will re stamp your new motor with the correct vin but it has to be ordered thru a dealership.