I had an experience with them and would never use one again. Purchased a boat with one installed, an engine motor mount had broken and I figured I would install a new drivesaver with the engine mounts to be sure everything was perfect. The bolts would not line up correctly on the trans flange or the prop shaft, when I finally got it in I could not line up the engine correctly. Tried a second one, same problem. After many many hours and wasted days of trying to line up and talking to their tech people I brought it back to the factory which was in Rockland Ma at the time. I explained the problem to the tech, he took the saver to the back to check it out, came back and said it was perfect and I must be doing something wrong. Went back to boat tried again same problem. Bought a micrometer and measured myself, they were manufactered incorrectly. Talking to many mechanics at the time, they had a good points, go metal to metal and line up correctly. Why would you want to be running a misaligned engine and shaft to have a drivesaver to correct, and also if the prop smashes into something that hard do you think the drivesaver is going to save you from damage.