hello this is my first time posting something, hopefully I'm doing it right. i tried to search np241 leak on this forum nothing came up for some reason, my question is i have 1991 k1500 np241 transfer case, i have a leak on the shift linkage o-ring, i have cleaned it up to verify leak, i removed linkage a drop of fluid came out of the range sector(gm name), do i have to open up the case just to replace o-ring or can i do it from the outside? thanks for the help