Complex sentence: Basically an upgraded version of the earlier ALCO RSD-4, and used in much the same manner as its four-axle counterpart, the ALCO RS-3, the six-motor design allowed better tractive effort at lower speeds.
Split into simpler sentences: Basically an upgraded version of the earlier ALCO RSD-4, and used in much the same manner as its four-axle counterpart, the ALCO RS-3. Though the six-motor design allowed better tractive effort at lower speeds.