I hope this isn't a duplicate, I seem to have lost a reply that I was working on. To make it quick, the Chev parts manual shows several numbers for 'switch assembly, coolant temperature' that cover the early-mid 60s. They are:
6400211 (62-63) stamped AC115B-226M
1993351 (64-66) G-10,Ser 10 thru 30
6402372 a whole series of models
If you would send me an address or FAX, I'll copy the pages and send them to you. Hope this is of use. RONDET
