I got mine from Napa a few years ago. It is a Balkamp Push Pull Switch. It has a part number similar to PPxx. You will also need the Electrical Harness that goes with it. It has a part # something similar to EC-22. I am sorry I can not remember the #, I bought it about 5 years ago.
It is a standard 2 speed rear-end switch (the red push pull type switch). I got the holder from a friend of mine who works as a fleet mechanic at a local Dairy (they have many trucks there).
I don't think the switch cost all that much, maybe $20, but the electrical connector cable did cost more than the switch, maybe $35. The cable is a nice high-quality cable, designed to connect to the PP switch.
It worked out very nice.