Thank you for the pictures. I put the reefer on the track with a Lionel box car, got a magnifier, and watched as I pushed the two together gently trying to get them to couple. There seems to be enough difference in the geometry of the new couplers to prevent the couplers from closing.
I have an RA number from Lionel, so I'll see if they have a solution - right now it seems (to me) the fix will be replacing the truck with the older couplers.