I recently upgraded a 2000 civilian crown vic from a 4g civilian alternator to a 6g police unit.
The swap added some additional charging ability (110 amps vs 130 amps). But was mainly done because the voltage regulator in the original 4g unit had failed and was no longer charging the battery. And I had a spare 6g police alternator avaliable, but didn't have any 4g crown vic alternators at the moment.
Since the 6g alternator was factory installed in our cars, all of the necessary brackets and wiring are avaliable from either your local ford dealer or the local salvage yard.
The "new" 6g alternator is on the left, the old broken 4g alternator is on the right
here's a top view of the alternators. notice the different regulator connector and the different orientation of the output stud
here's the regulator wiring pigtail to splice onto the civilian vehicles harness so that a police unit can be installed
here's the factory civilian charging harness. for my purposes, i'll cut off the civvy regulator plug and splice on the police one. the output stud wire has a little different contour to it near the terminal, but can be bent into shape with my bare hands
here's the support brackets for the alternator. the one on the left is the police 6g unit, the one on the right is the civilian 4g
here's the police alternator mounted on the civvy engine block
and here's a picture of the two regulator plugs side by side
and here's a police interceptor with a factory installed 6g alternator for reference