Just bought a JD project but do not know what year it is. Where is the frame # located? I have a lower end twin motor and the boss where the S/N usualy is is blank. It has not been ground off and looks like there was never a number there. Has correct HD markings on right case. Has straight gear housing so probably generatot model? and has outside oil pump mount. Holes in conecting rods. Left case marked "2-25" in raised numerals.