Got ahold of one of the new 3854 Operating Merchandise Cars yesterday, via preorder from the Train Station in Mountain Lakes, NJ.
What a neat car! A press of the button on an operating track section (you need to hold the button down the whole time) causes the side door to open, four packages to come tumbling out, and the door to snap closed.
The whole body of the car is metal -- it feels like die-cast -- and the trapdoor on top is metal as well. The PRR brown is nicely done. Even has little separate latches on the doors that don't operate, but do move.
Well worth $55 for an operating car!
It does not come with a tray, so you will need to find a way to catch the packages on your layout yourself.