Oil sender or gauge

[Gick70]

I was having low pressure on my factory gauge......so I plumbed a mechanical gauge in also....initial start both gauges are the same,ten minutes if that the factory gauge drops off drastically,is it the sender or the dash gauge??? 1952 flathead f1....

 

[19Fordy]

Probably the sender. This looks like it will work.
https://shoebox-central.com/1946-19...52-1953-ford-oil-pressure-sender-sending-unit
and here. The C&G sender below looks like the one on my 53 Ford V8.
https://cgfordparts.com/ufolder/fordpart.php?number=41A-9278-OR

Plus, do a search in the SWAP section.