Every DirecTV receiver sold today belongs to DTV and must be returned to DTV when you end service or replace the receiver. They called it a leased receiver but there is no lease fee, it's just a way that DTV maintains ownership.
If you can find an old R-15 DVR (SD only) that's about all you need. Since it will likely be used you will need to call DTV with the registration information to verify that is can be reactivated and you will likely need to buy a new card for $20. If you go new then it will be an HD DVR and the HR-24 would be your best choice. Any receiver with a model number of 25 or higher will require SWM hardware which you don't current have with your dome antenna. The SWM8 hardware can be added to many domes but I am not sure you would have success with a 2006 King Dome.