messicks is one of the most common.
for filters I normally hit a local dealership.. or if I have to.. napa..e tc.
if you still run into trouble, there is a user here named rickb.. he's a mechanic turned parts man that works for a NH dealer in new york.. I bet he'd mail order you a part if your local dealer or other online sites can not help you.
he's a straight shooter, and knows his business.
soundguy