WSOR 6641
| Model | Build Date | Builder's Number | Prime Mover | Horsepower |
| SD18R | 12/59 | 25621 | 16-567D2 | 1800 |
Unit History:
New Orleans & Northeastern 6950 (Built as a model SD24)
Southern 6344
Precision National Corp 1844 (Rebuilt as an SD10 by Morrison-Knudsen)
Chicago & Northwestern 6641 (Designated as an SD18R)
WSOR 6641
6641 sits in the East Johnson Street Yard (12/30/99)
6641, 6579, and 2052 in Janesville yard (3/13/01).
