The 2013 unit is now referred to as the Hustler Super Z HD (Hyper Drive). The HD uses the Grammer seat instead of what I call the Michigan Suspension seat that you have. Warranty, engine size, frame and deck remain the same. The 2013 Standard Super Z uses the 21cc pumps from previous years with our hot oil shuttle and cooler system, pneumatic front tires, your Michigan seat, and a 2 year no hour limit or 5yr 500 hour limit. Shoot me an email and I'll send you both spec sheets.