what year is your mustang?, is it a fox or an sn95 or a new edge or what.

I can tell you on fox coupes you just pop up the seat bottom and undue two little bolts on the side for the upper

on a fox hatch If I remember correctly you have to take out the little bolt in the center that holds the 2 uppers for the folddown together, etc, I 'm sure others can pipe in now that they're home from work.