Place the marrow and knuckle bones into an 8-quart slow cooker. Add enough water to cover the ingredients. Add the wine or vinegar.
Place the beef shanks and oxtails on a baking sheet and bake in a 350 degree oven until the bones have browned, appromixately one hour.
Add the bones and the rest of the ingredients to the slow cooker and fill with more water to cover all the ingredients. Set on high for one hour, then turn it down to the "keep warm" setting.
After 12 hours, turn off the slow cooker. Allow broth to cool slightly and then strain ingredients with a slotted spoon. Line a colander with cheesecloth or a flour sack towel and place it over a deep pot.
Transfer this pot to the refrigerator until the fat rises to the top and congeals. Skim off this fat and discard.
Transfer the broth to containers with covers that can then be refrigerated or frozen. The bone broth will stay fresh for 3-4 days when refrigerated. If frozen, it will stay fresh for 6 months.