[hharney]

I have the MT 3 blade props. This STC requires you to install both front and rear at the same time. The diameter of both front and rear are identical. 76 inch (192 cm to be exact). You can not install rear only or front only. You must do both. I have 185 hours on them in about 2 years. The TBO is 2000 hours or 6 years. The cost is very near the price of factory new McCaully's. Advantages: Smooth, very responsive, quiet, lighter (60 lb gain on useful), increase in climb performance (200 fpm) and sexy. The spinners are fiberglass and add a much improved look to the system. Problems: long delivery time, rear prop much more suseptable to FOD, only one service center (Florida). I have had damage to the rear twice. 5 minute epoxy and sandpaper. Overall I am happy with the performance and looks. Service and practicallity is a little questionable. I believe the workmanship is second to none. There are a lot of airplanes using MT blades.
BTW, be careful how you handle your current blades. The reason I had to install new blades, I had made the decision to overhaul my props and the shop condemed both units. They were working just fine before I sent them in.