Not really. Just the ball and the flap, but both come from the same part, the bottom of the sirloin (the three are separated from each other).
I cook in Cohoes from time to time. If I get a booking and can grab you one on the way in I'll let you know. Meanwhile, ask around. Ask, specifically, if tris can be ordered. Many places don't carry them - but don't know that they can (they don't even know what they are).