Place the chickens and the remainder of the ingredients in a 16- to 20-quart stockpot. Add 8 quarts of water and bring to a boil.

Lower the heat and simmer uncovered for a total of 5 hours, skimming off any foam that comes to the top. 

After simmering for 1 1/4 hours, carefully remove the chickens with a large slotted spoon or a spider spoon strainer.  Place the chicken on a large platter.  Once cool enough to handle, remove meat from the bones and set aside.  Place the chicken bones back into the stockpot to simmer for the remaining time.  When thoroughly cooled, divide chicken into four 8-ounce packets to be refrigerated or frozen for future use.

When the stock has simmered for a full 5 hours, remove from the heat.  Strain the entire contents of the pot through a micro-mesh colander and discard the solids.

Pack in quart containers and chill overnight.  If desired, remove any visible fat from the top of each container.  Refrigerate for up to 5 days or freeze for up to 3 months.