the 4 bolts holding the actuator foot plate to the side of the diff are quite soft and easily rounded off if they've corroded in place, that's the thing most likely to give you grief IMO. Before putting the new one on make sure the mounting face on the diff is nice and clean i.e. all corrosion and sealant cleaned off so the new one fits properly and runs along the correct axis. Don't put any sealant around the central part of the casing that interlocks or you may not get it back off in one piece next time! Do put a little sealant on the flat face, as a barrier to galvanic action as much as water ingress.