Heat vegetable oil in a large skillet over medium heat. Add the celery and onion; cook and stir until soft, about 5 minutes. Remove from heat, and season with poultry seasoning and pepper. Stir in the crabmeat, sherry, and bread cubes until everything is well blended.
Preheat a grill for medium heat.
Lay the chicken thighs out skin side down on a clean surface. Spread an even layer of the crab mixture onto each one. Roll up chicken and secure with toothpicks.
Place the stuffed thighs seam side down onto the grill, and season with garlic salt and onion powder. Cover, and cook for 20 to 30 minutes, turning occasionally for even cooking. Chicken is done when juices run clear when pierced with a fork.