if it is intact, and nothing is broken, it is pretty intuitive how to put it all back together. I can not think of how I did it the couple times i had it apart, but if you have basic mechanical skills, its pretty simple.
How did it fall off, do you know. I took mine apart years ago to replace the lamp, which I though was harder than it had to be....but that'* about the extent of what I remember. "Old-timers" ya know. I couldn't find anything specific about the shift indicator, just the console in general. The panel is held in by clips, so it should just pop off. Run into problems, let us know.
I haven't torn into it to see if anything is broken but, the way it started is the pointer would stick as I would put it into gear. Then the other day it came completely off. Not sure if it broke or not. I'll check it out in a day or two. Working too many hours right now.