One thing to remember is that nothing is too old for the crock pot.
Here is something I snagged that might be helpful:
Chickens fall into several classifications:
Broiler-fryer can weigh up to 3 1/2 pounds and is usually around 2 1/2 months old. These chickens, as the name implies, are best when broiled or fried.
Roasters, are more flavorful and have a higher fat content. They are perfect for roasting and rotisserie cooking, and usually range between 2 1/2 and 5 pounds and can be up to 8 months old.
Stewing chickens (also called hens, boiling fowl and just plain fowl ) usually range in age from 10 to 18 months and can weigh from 3 to 6 pounds. Their age makes them more flavorful but also less tender, so they're best cooked with moist heat, such as in stewing or braising.
Capon is a rooster that is castrated when quite young (usually before 8 weeks), fed a fattening diet and brought to market before it's 10 months old. Ranging from 4 to 10 pounds, capons are full-breasted with tender, juicy, flavorful meat that is particularly suited to roasting.
Rock Cornish hen, also called Rock Cornish game hen , is a hybrid of Cornish and White Rock chickens. These miniature chickens weigh up to 2 1/2 pounds and are 4 to 6 weeks old. Because of the relatively small amount of meat to bone, each hen is usually just enough for one serving. Rock Cornish hens are best broiled or roasted.
Squab Chicken (poussin in French), different from the true squab, is a very small, 4- to 6-week-old chicken that weighs no more than 1 1/2 pounds. These tiny birds are best broiled, grilled or roasted.
Cock or Rooster is an older bird and therefore rather tough. It's best used in soups or to make broths.
Free-range chickens are the elite of the poultry world in that, in contrast to the mass-produced birds allotted 1 square foot of space, each range chicken has double that area indoors plus the freedom to roam outdoors. They're fed a special vegetarian diet free (according to most range chicken breeders) of antibiotics, animal byproducts, hormones and growth enhancers. The special diet and freedom of movement is thought by some to give this fowl a fuller, more "chickeny" flavor; the added amenities also make these birds much more expensive than mass-produced chickens. Free-range chickens average 4 1/2 pounds and are usually around 10 to 12 weeks old.
