Wiper motor park problem

I am in the process instilling the windshield wiper assembly in my '67 barracuda and while testing the speed and park functions I discovered that it parks in the up or vertical position. The wiper motor is a newer '73 b-body that has been re-clocked to the right position for an a-body unit and the arm is part#3431618. Everything works fine except it parks strait up. The arm only goes on one way. I found an other thread about this problem but the info is not to clear on how to properly assemble it right.
Wiper motor parking up?

Just not sure what I am doing wrong,