Murphy Roofs and Camel Doors

Charlie,
The Murphy Roofs on the 3000 cars are the Metal roofs. The 4000 cars had the wood roofs (for the most part - I say that because someone will come up with a photo to prove the contradiction)
The Camel Doors on the 3000 Cars are the Main Side doors with the Metal re-enforcement around the edges of the doors and well as a metal Brace bisecting the door horizontally. Look at some old photos, you should be able to see the differences very easily. I have even started a list of 3000 with and without the Camel Door rought numbers are about 60% with and 40% without. To go along with the Camel door there is a metal strip on the side of the car itself. Also placed Horizontally it travel from the edge of the door opening down the right side of the car to about where the door stop is located.
Kevin