Break off crayfish tails, snap in half lengthwise, and lift out meat in one piece; discard tail shells. Snap off large claws (if desired, break claws with nutcracker, and remove bits of meat) and smaller legs; discard. Cut off top of head just behind eyes; discard. Scoop body shell clean, carefully removing and reserving yellow fat; discard intestinal matter. Clean and thoroughly wash 48 body shells, referred to as crayfish heads; set aside. Grind tail meat to yield 3 cups, reserving 1 cup for bisque and remaining 2 cups for Stuffed Crayfish Heads.
Melt bacon drippings and butter in a large Dutch oven over medium-low heat; add flour and cook, stirring constantly, 15 minutes or until browned. Add onion, celery, green pepper, and garlic, mixing well. Cover and cook 5 minutes or until tender. Gradually stir in water. Add tomato sauce, parsley, lemon juice, bay leaves, thyme, salt, pepper, and allspice; mix well. Stir in 1 cup crayfish meat and reserved crayfish fat. Cover and bring to a boil. Reduce heat; cover and simmer 1 hour, stirring occasionally. Remove bay leaves and whole allspice.
To serve, ladle into individual soup bowls over hot cooked rice, and place 6 Stuffed Crayfish Heads in each bowl.