If you have the old one take it to the National Air Parts Association (NAPA). They should be able to find a replacement from one of the old car restoration sources.
I have one that is either NOS or in pretty clean condition. It is the same as the one that Piper put on my 1969 Twin, so it is likely the one Piper put on yours. $36, USPS priority shipping included. Email kristin@theaviatrix.com.