Fantastic work, as always, Zulu!
My artillery unit just recently acquired our limber and carriage. We got a deal from another unit who had purchased limber components with the intention of building their own, but never got the project off the ground. In our case, the wheels and the chest were complete (or mostly so), and the package deal included the wheels, chest, and all remaining metal components. We got the entire lot for $2,000. The original plan was for me to do most of the construction work in my spare time, which I expected to take many, many months since that "spare time" stuff is pretty much a myth, I think.
However, since our group is county-sponsored (they actually own our 10-lb Parrott rifle), someone suggested we propose it as a project for the county technical school, which has a building and construction department. This was a win-win situation all around for us -- we got a dirt cheap limber and carriage, and the tech students got one of the most interesting projects they've ever made. They fabricated all the wooden components, and once the carriage was done rolled it on down to the tech school's automotive department and they did the painting. While they were at it, they repainted our cannon carriage with the same paint for an exact match.
Below are two photos, taken just before painting, of what a limber chest looks like once mounted on the carriage. In use, the carriage is hooked up to the back of the cannon to create a hefty two-part four-wheeled vehicle that can be pulled in a single unit. Embarrassingly, I haven't yet taken a photo of the two together.