MTH #20-21042-3 Richmond, Fredericksburg & Potomac E8 B Unit (non powered) Number 20-21042-3. Manufacturer MTH Trains. Scale O. $181.99. Add to Cart. Add to Wish List Add to Compare. MTH #20-21062-1 Union Pacific #6344 AC4400cw Diesel Engine w/Proto-Sound 3.0 (Hi-Rail Wheels) Number 20-21062-1.