To get the Red Hare harness, you need money, the development assignment, and the production assignment. The cities are able to develop the Red Hare harness are Nanman (in the Gathering of Heroes campaign) and Luo Yang (in all other campaigns). You must use development (in the equipment category) on that city three times. After that, you must then use production on Luo Yang. This will produce one Red Hare harness. If you want another one, just use production on it again.