If you have an electric temperature gauge in the cluster, classicparts.com has what you need. It is part# 53-811A. $24.95. It is for '57-'78 trucks. The write up they have for this part is pretty lengthy and sounds like it will work for your application.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission