Is it possible to install a factory, rail mounted dvd into a GM van which didn't come with dvd?

Our Pontiac sv6 is equipped with the overhead rail system which a factory dvd system clips into. I'm wondering how hard it is to install a factory dvd (available at auto salvage) into this van. Does anyone know if the wiring harness for dvd player would be in a van not originally equipped with a dvd system?Is it possible to install a factory, rail mounted dvd into a GM van which didn't come with dvd?
It is possible but very costly. The overhead harness does not come with the vehicle if it was not factory built with the DVD.

The harness is part of a body harness. It is about $800 for the harness alone. I know this as I recently repaired a vanthat had the DVD system stolen. When they stole the DVD the cut the wiring so we had to replace the harness too. It was quite an undertaking. Took 5 hours to install the harness. maybe the auto salvage yard can sell you the harness too.

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