I need to get a cable made to connect the speedo in my '56 truck to my English transmission. Does anybody know the thread size of the male part of the speedo on the back? My cable guy is asking and I haven't a clue.

Thanks in advance, folks!

 

My '54 measures 5/8" O.D. and is 18 tpi. It tapers a tad. According to my micrometer and this chart http://mdmetric.com/tech/tict.htm it is American 5/8" UNF. The threads are tapered a tad so I'd have to go buy a nut at he hardware store to be absolutely sure.