i seen a 400ex body on a 300ex could you do the same thing even if you had to modifify

 

400EX plastics mount right up. Although I dont think 250EX plastic will. But then again, you just never know.

 

I have both a 2000 300ex and a 1992 250ex.
I can take the rear fenders and seat and swap them just like that.
They look identical in shape and mounting but I have not tried swapping the front plastic not worth the work for me.
I do not know about the newer 250ex's if it will work.

 

You must be thinking of the 250X.

 

Oops yup, 250X.

 

almost everything on a 250x will mount up to a 300ex but the 250ex's are slightly different.