Thank you Tim
I’m not exactly sure it is correct. For sure, I know that it has been in the car decades.
The hardware on my antenna looks similar to what a listing on eBay states as correct for 69, 70 PM-300 hardware. ( see photo Snipet attached)
The obvious difference with the ebay listing, and the antenna I have is a metal chrome base vs plastic. The top chrome pivot, and body gasket looks to be the same.
Possibly this was replaced years ago.
Thks