Can you install a third row seat in an 07 Durango SXT without one?
I guess it is just cargo space right now.

 

It looks as that plastic piece can be removed and that is where the third seat would go. THe dealer should be able to tell you for a difinitive answer, but you can get the seat at www.mopar.com ,
FF

 

Go to a junk yard and get all the parts.

 

If you can find the parts in a junkyard, it's a direct swap out. Good luck finding the parts though. I had an 05 we were considering doing the same thing with. The only problem is the seatbelts for the 3rd row are designed to be shoulder belts that bolt into the ceiling.

You are better off finding a 3rd party custom fit 3rd row. Their belts will be designed bolted to the base.