I saw an ad for (I presume a used) autohelm 5000. I have the 3000 or 4000 on my boat (Catalina 36). I've been thinking of replacing it (it's 12 years old). I have heard that the X5 is just barely robust enough for a C36, and I don't want to go to the trouble and expense of installing a below-deck autopilot. I'm assuming that the 5000 is more powerful that the lower number models and would therefore be fine on a C36. Of course, there's a bit of a risk buying something like this used, so I'd want to get it at a really good price. My questions are: Is anybody familiar with this model and, if so, your opinion of it? Also, are the parts for one model interchangeable with another - for instance, can I use the motor and ring and keep the other parts I have already installed? Any other comments or thoughts. (By the way, we use our boat primarily for SF Bay sailing with a little coastal sailing.)