For stuffing, spread bread cubes in a single layer on baking sheets. Cover loosely with clean towels. Let stand at room temperature to dry overnight*.
In a large skillet, cook celery and onion in butter until tender. In a very large bowl, combine the bread cubes and celery mixture. Stir in the sausage, parsley, sage, thyme, salt, and pepper. Add enough stock or broth to moisten, tossing lightly.
Season body cavity of turkey with salt. Spoon some of the stuffing loosely into neck cavity. Pull the neck skin to back; fasten with a skewer. Lightly spoon more stuffing into body cavity. (Place remaining stuffing in casserole. Cover and refrigerate. Bake stuffing in casserole alongside turkey during the last 60 minutes of roasting or until heated.)
Tuck ends of drumsticks under band of skin across tail. If there isn't a band, tie drumsticks to tail with string. Twist wing tips under back. Place turkey, breast side up, on a rack in a shallow roasting pan. Brush with cooking oil. Insert a meat thermometer into center of an inside thigh muscle. Thermometer bulb shouldn't touch bone. Cover turkey loosely with foil.
Roast the turkey in a 325 degree F oven 3-1/2 to 4-1/4 hours or until thermometer registers 180 degree F to 185 degree F. After 2-1/2 hours, cut the band of skin or string between drumsticks so thighs will cook evenly. When done, drumsticks should move easily in sockets, and their thickest parts should feel soft when pressed**. Uncover the last 30 minutes of roasting.
Remove the turkey from the oven. Cover; let stand 15 to 20 minutes before carving. Remove stuffing from turkey; place stuffing in a serving bowl. Carve turkey. Makes 14 to 16 servings.
If you don't have time to dry bread, use purchased bread cubes.
The stuffing temperature should reach at least 165 degree F. To check, insert a meat thermometer through the body cavity into the thickest part of the stuffing and let it stand for 5 minutes.