Puzzler: 1954 Aluminum head temperature sender

Posted by longjohn On 2018/9/27 21:36:36

I am rebuilding a 54 359 with the aluminum head. There was no temperature sender in the head, only a plug where the sender should go. Upon removing the plug, I found that its diameter is 3/8 NPT, not the 1/4 NPT that every other post war Packard uses. I even have a spare aluminum head and it takes a 1/4 NPT!
There is no listing at Max Merritt or Kanter for a larger diameter temperature sender. They both show the same sender for all 51-54.
Is my situation unique? Does anyone else have the larger size hole? If you do, what temperature sending unit are you using?
I believe that there is an adapter available to reduce the hole size but I thought I would see if there is a different option.