Horse Drawn Vehicles for 55n3
Blue Moon Manufacturing
Blue Moon Manufacturing offers wagons in "28mm". They scale well for Scale 55. This is the Blue Moon Manufacturing Army Supply wagon. It is composed of excellent white metal castings and a resin body.
Knuckleduster offers this Studebaker farm wagon in Resin and white metal. Included is a well sculpted driver.
Imex for better Wheels
Imex has this 1/72 wagon train. It offers more delicate wheels and wagon frames. Everything else is too small. It is "soft" plastic and requires special primer for painting. There are ten sets of wheels and frames for about $30 with shipping on the net or $3 a set, cheap.
Google "28mm vehicles" and you will find a wide variety of options. There is a wide variety of nineteenth century vehicles and horsepower.