I was too, still am sometimes. When I hear a chime or see a light come on...
When you test drive it, be sure and go into the dash display and check for stored codes and oil/fuel filter life. Change all the fluids/filters, unless you have records.
That looks like a cowboy truck, make sure it is stock, or if not, that you are aware.
You will love how the exhaust brake/auto transmission work together. I recommend auto mode.