Parts needed: Rubber mallot, power drill and drill bit, socket set (10MM),
screws or rivots, GFX and metal moldings, a grinder to

This was done on a 1989 GT. It should work for all models.

First you have to remove the trim, this can be done be unbolting the screws
holding the black trim up. After the trim bolts are removed rip the trim
off, white clips are holding them up. These can be pushed upward and taken
off by just pushing up with your thumb on it.

Now you have the trim off and you have little knobs that the white clips
where latched on to. You have to either have to drill holes for these knobs
into the metal molding for the gfx, or you can grind them off. I put a
grinder head on my power drill and ground them off.

After the knobs are taken off, you have to put the front molding about 1"
above the edge of where the trim came off on the fender next to the front
wheel. Center the molding, drill the holes and either rivot the molding on
or use self taping screws.

Figure 1

After the front molding is on, you have to put the modling under the door.
When i took off my black trim, there where two dirt  lines that where
perfectly level, i used the bottom line as my guide line to center and lever
the molding. I then drilled the holes and mounted it with screws.

Figure 2

Now the rear molding must be put on, now this was pretty easy i put the gfx
on the other two moldings and taped where the top edge met with the fender
and taped it. I then measured the length of the molding and the side skirt
together, then measured down from the tape and marked it. I then drilled the
holes screwed the molding on and put the side skirt on.

Figure 3

The side skirt is on and looks straight, now you need to secure it. Jack the
car up from the rear end, and drill the holes in the bottom of the car that
are needed to secure it. I drilled them and used the factory screws to
secure it.

the Side skirt is now on.
Figure 4