Here ya go Greg. I got mine here.
Remember, it's an easy test to see if they're working. Just ground the switch on your - battery post and use a hunk of wire to go to the + post and threaded part of the switch. You should hear an audible click when you touch the + post with the wire!
Oh, one other thing, OEM (used) is fine. But unless they're new in the box, I found out that after 30/40 years on a truck, the plastic starts to leak. That's why you see so many of them with epoxy all over them. I finally just went and got a new one at
http://www.oreillyauto.com/site/c/search/Fuel+Tank+Selector+Valve+-+Universal/N2000/C0025.oap