In a medium-sized bowl combine the ground round, ground sirloin, and ground chuck. Combine and mix. Allow meat to rest about 10 minutes in the refrigerator before forming 4 - 4-ounce balls of meat.
While the meat is resting combine the salt, black pepper, onion salt, and garlic salt in a small bowl. You will use this burger seasoning on the burger.
Prepare the Frisco sauce by combining the thousand island dressing, French salad dressing, ketchup, and Worcestershire sauce in a bowl.
Preheat the griddle to 375 degrees, if you do not have a griddle I suggest that you use a large cast iron pan. If you have a large griddle butter 4 pieces of bread on one side, and allow the bread to toast on the griddle while the burger cook. If you do not have a griddle you may want to toast the bread on one side in your skillet before you cook the beef.
Once the cooking surface had heated up fully place the meatballs onto the skillet. You will need to press the burgers into thin patties. Use a spatula to press the burgers into thin patties. Season with the burger seasoning. These burgers cook very quickly 2 to 3 minutes on the first side. Once the edges begin to brown flip the burgers and season them again. Place the 4 slices of cheese onto the meat patties. They will need to cook for another minute or two before they have cooked through.
To build the burgers spread the Frisco sauce on the untoasted portion of the bread liberally. Build your burger starting with a piece of the toasted bread, and then place a meat patty topped with Swiss cheese, and then one topped with American cheese, and top with a piece of toasted bread.