Once the 'case is clean, you'll have to make room for the larger gears inside the housing by trimming/cutting a total of about 11/48 inch off the transfer-case housing. Put the new low output gear inside the housing and mark where it makes contact with the oil gutter. Mark the depth of the cut. Then, measure and mark the gutter in the center T-case housing. Use a circular saw to grind away just enough material to make room for the gears.