rare 73 dart sport?

Hi there, my name is Erin and I'm from reno nv. I own a 73 dart sport with some unique options. Im not quite sure if the car is more rare than others. It has a sun roof and looks to me like it is factory. Is that a common feature on these cars? It's also a four speed manual and its petty blue. How do I know if the sun roof is factory?