Can someone explain the diagrams showing the l-r 1.2.3 pin location indicating ccw on the left and cw on the right while other diagrams shoe l-r 3.2.1 ???
I am really unsure of your question. Each part would have their own data sheet. Bourns does multiple styles on their trimmers with the same base part number. Though they do change with different pcb pin layouts on the same data sheet. I guess without having the part number , I am trying to understand what your question is. We would need more information on the part series you are looking at to make any kind of answer for the question you have.
The reverse pin order is probably due to the internal routing of the terminals. In the “Y” model, the resistive horse-shoe shaped track is most likely upside down compared to the “M” model. The terminal locations do not suggest the internal routing.