They'll make fine stewers, or if you have a pressure canner, you can can them and the meat will get tender. I cook my oldies in the crock pot, usually, and just leave them on until the meat comes off the bones easily. Take the meat off and use it in all kinds of dishes, mexican, or pasta, or whatever. Save the broth, it'll be wonderful. I chill mine, remove the fat and use that for cooking, freeze the broth to use later in soups, sauces, stuffing, gravy, or to cook dumplings. It'll be darker than you're used to seeing, that's ok, it's just much richer than from a younger bird.
For birds as old as yours, it's a good idea to brine the meat before you cook it. Just soak it overnight in the fridge. I use 1 TBS. salt per quart of water, and an equal amount of sugar to cut the harshness of the salt. Some use a higher percentage of salt, this is just how I like it.
Here's a link to some brine recipes.
http://www.bbq-porch.org/brining06.htm
The reason for brining is that water and salt are attracted to each other, salt in the meat tissues help keep the meat from drying out. It's odd, but meat can be dry even when cooked in liquid. Brine helps reduce the "stringiness" of an older bird.
I find that even if a bird does get a bit stringy when cooked, the meat is still very tasty, and if you chop it up and use in enchiladas, pot pie, or whatever, it won't be noticeable. Everybody will just tell you how good it is.
Enjoy your meals!