Preheat oven to 350°F and grease a 9x13 baking dish.
In a large bowl, combine the ham loaf, ground pork, egg, graham cracker crumbs and milk.
1 pound ham loaf, 1 pound ground pork , 1 egg, 1 cup graham cracker crumbs, 1/2 cup milk
Use a 1/3 cup measuring cup (or a large cookie scoop) to make balls out of the meat mixture and place into prepared pan; set aside.
In a mixing bowl, whisk together the ketchup, tomato sauce, vinegar, brown sugar and yellow mustard.
1/2 cup ketchup, 1 8-ounce can tomato sauce, 1/4 cup vinegar, 2/3 cup brown sugar, 1/2 teaspoon yellow mustard
Pour the sauce over the ham balls and bake for 50-60 minutes, or until the ham balls reach an internal temperature of 160°F.