I just got what you are asking for ordered in. I got it from Denny's Trailer sales in MN. You could ask them but doubt they have one sitting around but they could quote you a price on a new one. They hold their value so a used one might not be that much cheaper than new. http://www.dennystrailersales.com/
i am an alum-line dealer and we have new and used trailers available. we can make a new one to fit your needs or have many used goosenecks of all brands also. my number is 3197509206 you can give me a call anytime. thanks Marc Davis