Freight cars and cabooses on the USMRR at Alexandria

I am preparing for another trip to the National Archives to continue research on the USMRR. In reviewing the documents I collected nearly two years ago I noticed the following chart which lists the types of cars in service on the USMRR Virginia in April 23, 1863. Note that the USMRR had 654 freight cars at its disposal, with 191 at Aquia Creek. The cars at Aquia Creek were comprised of 84 box cars, 106 flat cars and 1 passenger car.  Note that there were no stock cars listed at Aquia Creek.

On June 1st the USMRR reported 88 box cars and 79 flat cars, with no passenger or stock cars at Aquia Creek.  This data will help me size my car fleet.  It will be a shame to not have any stock cars on the layout, so I may freelance that a bit, but note that stock cars comprised only 1 percent of the fleet. I do find it odd that I have a picture showing a conductors car in use as a telegraph hut at Stoneman's Station, but these reports make no mention of conductors cars until September.

In the similar report for September 1863, there is a new class of cars listed, cabooses (see the highlighted section of the report). The word caboose has also been added to the box car roster shown below. These are the only occurrences of the word "caboose" I have so far seen in a civil war era documents . Has anyone else seen this term used in the ACW?

Also note that 16 box cars were used as offices and 2 for hospitals.

Finally, the next three  documents will very important to the freight car builder as they list the road numbers for each type of car in service on the USMRR at the time of the report.  These essentially form a roster of equipment, although the exact types of car are not listed. There are more pages available, but this should help you if you need to accurately number your freight car models. Click for larger images.

Stock Cars

Box Cars

Flat Cars

All of these pages came from the same book of USMRR Car Reports at Alexandria. The list of car numbers were the first pages (you can see the page numbers on the sheets),but were not dated. Presumably before the first quarterly report listed, which was Sept 1862. They could also have been adding car numbers to the roster as the cars came on board. The fact that there are different color inks used to enter the car numbers seems to hint that it was updated as cars came in, but I don't know for sure.