Front end.
 

I have a question can you replace the front nose of a 2001 Grand Marquis with a front nose of a 2001 Ford Crown Victoria? And is there a minimal modification to do it?

It depends on what you mean by the nose of the car, do you mean just the bumper cover? Because that might fit, but if you mean the core support, header panel, crash bar, ect..., it might not. The best way to tell is to go to the junk yard and poke around and see if the construction of the front ends look the same