Some time around 1955 they went to cast in ears. So yours is probably ’54 or earlier and judging from slightly squared off look, it might be a ’53 but basically the same as these pictures.
The diaphragm for the tanks with the metal push button have a hole in them for the stem. If your diaphragm needs replacing compare prices. The ones without the hole (later tanks with black plastic button) tend to be cheaper. Then just place your bad one over the new one and mark where the hole is and punch it out yourself.
I personally like the pressure tank system. Others have their own opinion. Sometimes I’ll convert one for someone else but I always make sure it runs ok off the pressure tank first. Then if you have a problem when you convert over you pretty much can isolate it to fuel pump/fuel delivery, etc.
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