You cannot run that motor without t-stats!!! It also does not have a restrictor on water indicator so all you will get is free running water with lil pressure and the t-stats have nothing to do with indicator flow. Some will lean spit on the hose due to lack of back pressure but need to check...
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