There are a couple of popular choices. I run this one, and it works great. Plus, it has a nice connection I can use to connect my temperature gauge.
http://www.vintageprecision.com/
I formerly used one like this, which goes into the top radiator hose. This model tends to migrate inside the hose toward the radiator over time.
https://www.snydersantiqueauto.com/P...earchByKeyword
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