Can you change pre 97 front door windows to post 97?

One of the main things that annoy me about my front side windows is that useless little triangle of glass by the rear view mirror. I noticed that 97 and up have the entire glass slide up and down, but not the pre 97s. Has anybody done a conversion to the later style of door window glass? I'm guessing it would be possible as long as you have a donor door to swap parts, but maybe I'm oversimplifying it.

Probably be easier just to swap the entire doors. I did it on my old 96 XJ and on my present 92 MJ.

I agree with johnnyc, I would be much easier to replace the whole doors. I had the same idea as you, but after looking at i just went to the pick and pull and snagged a couple of doors.