Before super dooper fishfinders and GPS units it was fine to run non resistors. If you have not been having any interference problems use the non resistor plugs. 0.04 =1MM=.039 so plugs are gapped correctly.
Here ya go..
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwj69e6D0cTyAhWSbc0KHYFFDxsQFnoECAoQAQ&url=http%3A%2F%2Fwww.hedges-uk.com%2Fboat%2FC-90-86133.pdf&usg=AOvVaw3r5ilzcdju5n3tTrNFqbcw