I still haven't checked my thread size yet but your pic of that temperature prob looks just like mine. I have a couple concerns though that I need cleared up. First off is: The threaded fitting in that picture has 4 flat sides in it to allow the probe and Bourden tube to pass through the back of the guage.What keeps it from leaking around the fitting? Second issue: My Bourden tube does not appear to be long enough to reach the threaded hole in the DS head (I'm trying to keep the smooth firewall appearance) So I'm wondering if I could thread it into my Edelbrock intake manifold between the carb and the distributor? Any help would be appreciated. Thanks