I have two super z's already and I am looking at buying another one. I found someone selling what he claims to be a 2007. I just e-mailed him for the serial number off both the mower and the engine. Anyways the mower only had 5 hrs on it and was only used for his own house. I have heard there were several updates to the XR-7 deck as well as the 30HP Kohler. I was curious what serial numbers for both the engine and deck are the "good ones" and not older ones with problems. Both of my current super z's have the older deck and not the XR-7.