I have a chrome valve cover breather on my '65 300, which I'm not sure is original. It is definitely old, and almost looks to be original, but I can't tell. None the less, the guts inside are wasted. I'm looking for ANY very good condition breather (preferably another chrome one). If it's not chrome - no big deal as long as it's nice. Thanks, Matt grnlark@cox.net
Year One sells brand new reproductions of the chrome oil filler cap/breathers just like you are talking about. Never seen a chrome one on a 300, but they are the same as the stock one except for the chrome.
