Factory setup uses a shim under the front (largest) bearing. Take care not to damage it when removing the race and re-use it.
They also use the slinger to shim the bearing out where one is fitted.
If you need to adjust the pinion depth you can leave the under head one out and adjust the depth with shims under the shell.
+1 means the pinion was manufactured at 1 thou over std depth setting as measured from the face of the pinion head to the ring gear centre.
HTH
Mik