Heat oven to 350°F. Line a 9x5-inch loaf pan and lightly grease.
Stir stuffing mix with milk and Worcestershire in a large bowl. Let stand 5 minutes.
Add beef, eggs, onion, garlic, ketchup, salt, pepper, and parsley to the bowl.
Mix gently with your hands until just combined; avoid overmixing.
Press the mixture into the prepared pan or shape a loaf on a lined sheet.
Whisk ketchup, brown sugar, mustard, and vinegar for the glaze.
Spread half the glaze over the loaf.
Bake 35 minutes.
Brush with remaining glaze and bake until 160°F in center, 18–22 minutes more.
Rest 10 minutes before slicing and serving.