You don't need the "front" diff to move the truck. Because he has ADD and not manual hubs, you will need to pull the axles half shafts out, if he's going to actually drive it. Just undo the bolt or clip that holds the axle into the hub and slide them out, once the diff is already out. Then you can pretty much drive it all you want, just no 4WD.

For the rear diff, you can bolt your stock rear diff into his truck so it can be driven and moved. In fact, you will need a diff in the rear axle to move the truck, since the diff supports the axle shafts and thus the tires.