... my 3.5" OD Rudder Stock (1/4" SS pipe) has a stop collar around it made of Aluminum, it's 3.5" ID pipe, 1/4" wall thickness and about 1.5" long, bolted on either side to the Stock with 3/8" bolts, tapped. This rides on a plastic washer, that is probably 25 years old and probably something like Delrin, it is 3.5" ID, 5" OD and 1/4" thick. That sits on top of my bronze Stuffing Box Cap, and is not fastened. I'm replacing the Stop Collar and the Washer. Am thinking Delrin from McMaster-Carr and have that machined locally to spec., they have a PTFE-filled Delrin Acetal Resin in rod or sheet, that is supposedly more slippery and more water-resistant than plain old Delrin. Someone mentioned Duralon. Is there another product I should consider or go with the PTFE Delrin from MMC ? Thanks, cheers, John