Warm a large skillet over medium-low heat. Add the smoked meatloaf slices and heat for about 2 to 3 minutes per side, until warmed through. Transfer them to a plate.

Spread butter on one side of each slice of rye bread. Spread Thousand Island dressing on the unbuttered side of four slices.

Place one slice of Swiss cheese on the dressed side of each slice of bread. Add a warmed meatloaf slice and divide the sauerkraut evenly among the sandwiches. Top with the remaining bread, buttered side facing out.

Cook the sandwiches in the skillet over medium-low heat for about 3 to 4 minutes per side. Press gently with a spatula and turn when the first side is golden. Cook until the bread is toasted and the Swiss is melted.

Transfer the sandwiches to a cutting board, let them rest for a minute, then slice and serve.