I wasn't quite sure of the mounting arrangement. This illustration shows pretty much what I was assuming. I had not thought to look at manuals of other tiller pilots... makes sense though.

The round "donut" thing is what I have already mounted on the boat... what I need to make is the item with the L dimension. Not sure if the Raymarine version would work for my tillerpilot 2500. But at least this illustration, and the measurements they are discussing, are in the same range as what I have.

Thanks