Place marrow bones in a 10-quart** slow cooker and cover with filtered water. Add vinegar. Allow marrow bones to soak in acidulated water for 1 hour.
Place the oxtails and neck bones on a baking sheet and roast in the oven at 425°F until well browned, 45 minutes to 1 hour.
Once the oxtails and neck bones are browned, add them to the slow cooker. Deglaze the baking sheet with filtered water and add it to the slow cooker.
Turn the slow cooker to high and bring the water up to a boil. As soon as it comes to a boil, turn the slow down to "keep warm". When it comes down to the "keep warm" temperature, it should register 180°F. (You can check this by inserting a cooking thermometer into the liquid.) This is the perfect temperature at which to make bone broth. If you are doing this on the stove top in a stock pot, turn the heat down to the lowest setting.
Skim any foam that floats to the top of the liquid.
To the slow cooker, add all of the remaining ingredients. Add additional water to cover.
Place the lid on to the slow cooker and simmer on the "keep warm" setting for 12 hours.
After 12 hours, turn off the heat and remove the bones and all the other ingredients from the broth. Do not discard the bones. They can be used to make a second batch of bone broth. If you are not going to make a new batch of bone broth immediately, the bones can be wrapped well and refrigerated for 2-3 days or frozen for 2-3 months.
Strain the broth through a lined colander or strainer (you can line it with cheesecloth or a flour sack towel) into a bowl. Refrigerate. The next day, the fat that has risen to the top of the bowl and solidified may be removed and saved to use for frying. The broth should be quite gelatinous and can be gently warmed on the stove top and consumed as a beverage or used as a base for soups, sauces, or gravies.
The broth will stay fresh refrigerated for 2-3 days or 2-3 months if frozen. If the solidified fat is left intact on top of the refrigerated broth, it can create somewhat of an airtight seal and will keep the broth fresh for about one week.