It is all in the prep work. Are you just replacing the towers or the aprons too? Why are you replacing them? If your just replacing the towers they will line up with the old marks and the holes in the aprons and frame rails. If your replacing it because it won't drive straight because of an accident etc, I would reccomend the whole frame rail. I took the tower only route on my first mustang only to have to do the whole frame rail when the tower didnt fix it. NPD has a COMPLETE frame rail, shocktower, fender apron assembly Pre-assembeled for only 550 bucks. It basically depends on what you are doing it for.
Just the shock towers. Aprons and frame rails will stay in place. My shock towers had cracked and the bottom piece had seperated at some time in the past. It's been welded by a PO. It drives fine and the cracks have not come back.
I'm mainly thinking of replacing them for cosmetic purposes. And I don't know how the previous repairs will hold up when I start pushing it harder (more power and some suspension mods).
I was thinking that with bolt holes in place it would not be too dificult, but I want to make sure.