I have had a hard time finding an answer on whether my CCV filter or air/oil separator needs to be replaced. I know the newer models have a filter that plugs up, but these older ones do not have a filter. However, lots of people online say they replace it anyway.

Looking on RockAuto, the entire assembly is not sold, but they do offer a diaphragm replacement:
RockAuto

Lots of auto parts stores offer the same part.

Has anyone had any luck with replacing the diaphragm only instead of the entire CCV box? Is Dorman right that only the diaphragm needs to be replaced?