49 experiences the higher load fig4 schematically illustrates the case in which the propeller shaft 56 is rotated counter clockwise as seen from the rear of the outboard engine 40 indicated by the arrow the helical gear 80 is right handed the helical gear 82 is left handed and the driveshaft 49 is driven with a higher load than the driveshaft 48 in this case the helical gear 82 will move upwardly as shown the effects of other combinations of these parameters should be readily understood by persons skilled in the art and will not be discussed herein in detail once the helical gears 80 82 have reached a stable configuration in which the load from the bull gear 88 is evenly balanced between the gears 84 and 86 the helical gears 80 82 no longer move vertically relative to each other the helical gear 82 is raised with respect to the helical gear 80 by a distance l shown in fig4 the distance l is measured using the position indicator at step 200 a shim 94 shown in fig4 is selected having a thickness l at step 210 the shim 94 is inserted below the shoulder 91 of the raised helical gear 82 to maintain it in the raised position corresponding to a balanced load between the helical gears 80 82 for example if the distance l was measured to be 0 5 mm at step 190 a shim 94 having a thickness of 0 5 mm will be selected.