I get mine from marineengine.com about $5.95 each with $7.95 shipping in the US. The one with the hole for the older style is about $16, so I also punch a hole in the $5.95 ones and save quite a bit. I don’t think an empty hole is worth $10.00. Other than missing the little hole the diaphrams are identical. They have basically everything to rebuild the tanks there.
OMC brand old style with the hole 376455
Newer style without hole, (for the black button tanks) 305715
marineengine.com 800. 209. 9624