741 open to 489 suregrip swap

You can check the condition of the sure grip before you buy if you have a couple of axles and a friend. With the chunk laying on the ground or floor,Stick one axle in one side and the remaining axle in the other. Have your friend twist his axle one way while you turn yours against it. It should not slip at all. Which ever of you is stronger should be able to flip the other guy. Some units will "click" some will openly slip but when the engine torque is put on the unit, it will be a lot more force than two guys with axles.