- 20:23, 2 October 2007 diff hist +12,434 AY Honor Model Railroad Answer Key discribed mechanical refridgeration, and RBL cars.
- 19:59, 2 October 2007 diff hist -26,133 AY Honor Model Railroad Answer Key Added more details on car types, loads, ans construction
- 19:15, 15 September 2007 diff hist -18,770 AY Honor Model Railroad Answer Key added details and corrected errors.