mine came with a shorter arm that could fit on but it does not have the D-slot to aline it on the VB shaft.

maybe that could be clamped tight after the shifter cable is installed and both shifter and trans in N detent.

like I siad,i get to the point you are at. i can get it to either up shift correct and not down shift. or down shift correct but not up shift correctly.

if you seem to think a short arm moveing the cable end in closer to the trans case will work maybe I will swap the arm out on mine and try 1 more time.