There are two main types of attaching standards: Thetford (who has been doing this since the Year Gimmel) and I forget the other one. I am sure someone will rush in to add the name. Parts and adapters between the two types abound.
If you have one that is neither of those, congratulations, you may have discovered the Lost Ark.
Seriously, if the connector you want to replace is original, it is Very likely a Thetford connector. Airstream used those for a loooong time. My '74 Sov uses Thetford, but brand new ones don't, so they changed over somewhere in that 40 year slot.
Look for Thetford parts at any established RV parts and repair place. If they don't know what Thetford plumbing connectors are, RUN out of the shop.
[Edit:] The other type is Valterra