1963 40 hp wiring harness boat side info

[xtremefisher1]

hi everyone,i have a 1963 evinrude 40 hp boat side with the flat connector with the little metal box on it for the voltage regulator and everything else inside.


my question is can i change out that metal box to a plastic one with seals on it or do i need the metal one for a ground source? the reason i want to change the box is because i want more room in the box for working on any connections that may need to be fixed at any giving time while either on the water or on shore.


thanks for the help