Grilled Meatloaf

1 pound 80/20 ground chuck 1/2 pound ground pork 1 cup dried bread crumbs 1 cup finely chopped onions 1 16 ounce can tomato sauce 3 Tbls apple cidar vinegar 3 Tbls brown sugar 2 Tbls yellow mustard 1 Tbls worcestershire sauce 1 tsp salt 1 tsp black...