If done right the MK bellcrank is a far better system than pull pull. You have virtually infinate range of adjustment of both elevator halves and there is not worry when taking the stab off that the elevators will be out of alignment (with pull pull that will happen from time to time). The trick with the bell crank is on the pushrods that run from the external arms of the bellcrank to the elevator, the thread pitch on either end must be different ie: 6-32 one end and 4-40 other end. Doing this that pushrod can become any length that you want, if they are the same 4-40,4-40 at each end then you limit yourself to a half turn minimum adjustment.