2007 – Like the caption says, this is a 1973 Dodge extended cab body on 2006 Dodge Cummins Diesel 4 X 4 platform.  The interior is all 06 Dodge, seats, dash, floor, everything.
This is what the 06 looked like when I bought it as a one year old truck with only 20,000 miles on it.  The previous owner was doing burnouts when the rear tire wore through the cords and burst.
And this is what the 73 Dodge pickup looked like.  I found it in Las Vegas.
The most difficult part was moving the front fender wells back 9″ to line up with the front wheels, this due to the more cab forward design of the 06 platform.
It turned out to be a great little truck.  I sold it to my across the street neighbor Dan who lets me borrow it when I need a big truck and he gets to pay the registration and insurance.