I changed the fork oil today. The rubber washers on the plugs on the top of the fork caps were getting pretty chewed up. I got looking closer. They are the exact same size as the rubber washers that go inside a garden hose. Pack of 6 at Lowe's is 97 cents. I don't know what the dealer gets for genuine HD ones, but I'll wager it's considerably more.
Still good info. I might change my fork oil and there's a good chance are I won't think about picking up the washers from the dealer. I have garden hose washers in the shop. Would let me finish the project instead of waiting til the next day or weekend to get to the dealer.