As a Construction Union Millwright I have rebuilt gearboxes/gearsets in the heavy industrial sector, i.e. Powerhouses, Steel/Aluminum Mills, etc.
Most of the gear sets are single & double helical gears and some straight.
I have rebuilt several automotive diffs and depending on the system, some require limited slip additive for the clutch packs and any friction modifiers will causes the clutch pack in the locking differential to slip and miss engagement.
I don't know enough about our front diff/final drive to make a contribution about additives, however, Yamaha does recommend "Yamalube Friction-Modified Shaft Drive Gear Oil 80W-90".
So based on that I think it would be suffice to say go for it and let us know your results.