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You're in luck, you don't have to open the differential. Those stub shafts go in and engage the side gears in the differential carrier on one end, and obviously the axle shaft on the other. The stub shaft locks into the side gear with a clip much the same as the clips that hold the cv shaft to the stub shafts. All you'll have to do is get the stub shaft removed from the CV shaft, and pop the stub shaft back into the differential.