I was looking for the same, since I cannot fit the slim 1/4 in my kegerator along with a corny.
I'm not sure where in NY you are, but I spoke with Boening Brothers, who distributes Yuengling on Long Island, and they stated that they do carry the 1/6 kegs. I had asked several of the retailers near me and nobody was able to give me a definite answer, so I went to their source.
Check this link to find your local Yeungling distributor and contact them for more information:
Yuengling New York Distributors - America's Oldest Brewery