ok, so i searched through the service manual and CAPS. the shifter arm is part of the 'control shaft'. apparently, the arm is some how pressed onto the shaft, and is sold together with the shaft as a unit.
why do you need another shifter arm? it appears that you did the "short shifter mod" to yours by drilling a hole in the arm. even with that hole drilled, you should still be able to use it just fine. are you wanting to drill other holes?