You can find lots of general information with the options code plates (metal business card sized, attached to the top edge under the hood of the driver's inner fender). Go online and punch in something like 1971 Plymouth Fury build codes, there are quite a few guys/gals out there that like to share information they have found. Is the car intact enough that the rear seat containing the original build sheet is still there? Usually stuck between the seat springs and foam rubber.