Available for sale, Hydraulic Truck Drives, fits standard truck, built for a Balfour Beatty ballast cleaning train to drive the 4 car, total of 6 drive axles on 4 trucks. They are two speed, 125 HP input. Input is 50 RPM. Ratios of 10.44:1 and 90.61:1 and are hydraulic drive. $7,500 for single drive unit, $9,500 for double drive unit & $6,000 for a drive axle with no truck. 

Would work great for building a self propelled rail vehicle . 

Original machine in operation: