Boyd rebranded the three N Scale horse-drawn wagons made by Roskopf and sold them in blister packs. Evidently it was pot luck regarding the color of the horses. Note that Preiser also used to rebrand these same sets. Evidently a fourth wagon was made, a water wagon, but I've not yet learned the original catalog number.
Where to Buy
These are extremely hard to come by, making rare appearances on eBay.