Someone who "hacks" Tesla's like Jason Hughes (wk057 here on the forum) can probably do it using salvage motors. He did turn an original 60 into a P85. It would require changing both motors, the 60 has one large motor in the back and the 60D has two small motors. The front end would have to have some equipment added to support the front motor and extra wiring would have to be added. It would not be easy and if you paid anyone to do it, it would probably cost more than selling your current car and buying a 60D.