Ray - Adjust on the bench! I found this out the hard way when the guy who rebuilt my wipers didn't bother to position the park and I installed it in the car like that.
Rotate the top cap to the desired park position by trial and error.
With the motor on the left and wipers to the right, as if you're in the car, you want it to park at the leftmost position.
Once it parks on the left, you can install it and fiddle with the positions of the wiper arms on the splines. What you don't want is, when switched on, for the wiper to continue downward onto the hood.