That would be great to find an OEM part for it cause the metal part is bullet proof but the cancel nubs are plastic. All of the used ones I found had the cancel nub broke off on one side or the other. I don't think anyone re-produces the plastic part but anythings possible these days. What I ended up doing because the parts suppliers kept sending one for a 65 chevy, was to get a signal cup that holds the switch from a 65 chevy. For whatever reason the GMC stuff is different how it bolts up or screws down, thats how I fixed mine. Latter I ran across a link that may work for you, but then again I don't know for sure if it's what you need for your 64 it don't hurt to look though good luck..Vernski
http://www.1aauto.com/1A/turn-signal...TS00063/326098