All - I have a 1941 Willy's MB slate grill that I finally started restoring. I am working the front axil and in process of reassembling. I realize the knuckle should be bare metal, but my question is how much of it? It seems that not all of it needs to bare metal. How did it come from the factory? And given it is bare, does it require periodic maintenance (i.e. covering in oil or grease) to keep it from rusting?