In the trains my Uncle Jim left me was a 5590 crane I didn't know he had. sometime in it's life, it had Lionel baseplates added to the Marx trucks. I swapped these out for the correct Marx til couplers. My question is on the roller pick up Marx used. I found a pic of oe on the bay, ,but I can't tell how it connects to the truck.Any one have any idea?Thanks!