To get the Red Hare Harness, you need money and the Development and Production 
assignment cards. The cities that 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 the Development assignment card (under the "Equipment" 
category) on that city three times. After that, you must then use the Production 
assignment card on Luo Yang. This will produce one Red Hare Harness. If you want 
another one, just use the Production assignment card on it again.