I bought my pumps for my 1967 337b from
https://aircraftaccessoriesofok.com/
Duke 4140-00-15 This was the physical part # on my pumps Luckily I had a couple spares from a 1967 337b parts plane
They had them in stock but you must return your cores There is a core charge which they return if your cores are good I had some extra pumps kicking around so I sent them in and they confirmed that they were good cores so i was never charged the core charge
I had to replace my pumps with an original the dukes the other pumps for the newer 337's are not certified for the older models
Pull the panel and see if you can see the part # on your pump
Hope this helps
Frank