You can use 2 hammers if there is room to get a good swing at the side of the knuckle. Use a sledge to hold against the back side of the knuckle and add additional mass to keep the joint from moving. Then use a large ball peen hammer to rap on the other side of the knuckle. This will usually pop the tapered joint loose.

95 Montero SR, 189k miles
89 Dodge Raider, 189k miles