Thinks to look at when buying D6N

My cat dealer brought out a 2006 d6n lgp for me to demo and im kinda thinking about buying it but wanted to make sure i wasnt overlooking something on this machine or buying a piece of crap. For starters it has 4500 hrs, vpat, lgp, fourth valve, erops diff steer. Undercarrage is shot imo so they are going to throw a new bottom in on the price minus the labor. Also the cutting edge looks like it was just flipped, tower bushings seam tight also. Appearance id rank it as "good", but obvious it wasnt in a shed any of its life like typical construction equipment. It was at a sister cat dealer in MO as a rental until now. The are wanting $102xxx. Any input