I had a little bit of free time tonight, my son's Scion Tc frame off restoration doesn"t start until Saturday, so I decided to make a little Mustang progress. Since the Passenger side is the worst, I figure I'll do that side first.
So I started by trimming my donor section. Actually, I started by starring at the donor section, and the car for a while, I took some measurements, and here's what I came up with, the rail itself measures the same, it's probably stamped on the same tooling they used on the fox body's, it has several different holes that the foxes don't have, the sway bars mount differently, but you could weld the fox sway bar mounts to the new edge rails, which is what I will do, and there is no hole for the bolt for the front bumper absorber, but if you're skilled enough to replace a rail, I'm sure you can figure out where to drill the hole.
The strut towers are the same size, they would weld right in where a fox body strut tower fits, but the top where the strut bearing plate bolts to the tower is different, you could probably use the bearing plate from the new edge and it would work out fine.
The aprons look to be similar, but the radiator support mounts to them different, and the holes for air boxes and other accessories are different. I don't need aprons, and these aren't close enough to use anyway.
So I did get the pass side donor trimmed out, I'm not putting the whole rail in either side, this car has been hit in the front before, and the radiator support has been replaced. Whoever replaced it back in the day did a good job, but none of the factory spot welds are there, it's plug welded and stitch welded in a few spots and I don't want to mess with it.
Anyway, here's some pics.
Passenger side donor section, those big odd shaped holes at the front of the rail wouldn't be used for anything on a fox, and somewhere between them would be a hole for the front bumper absorber.
This is the first part I need to trim off, at the junkyard I just ruff cut around the rail with a Sawzall.
This is the spotweld drill bit I'm using, it has a small cutter in the center to act as a pilot. You can see i have already drilled some of the welds in this picture.
Here is the other side of the rail, the spot welds are drilled, you only want to drill through the first layer of steel, or you will end up with a hole in a spot where you need to weld later. I also cut that little stitch weld with a cutoff wheel.
Here I have it removed, after I drill the spotwelds, I use a panel separator and a hammer to peel the pieces apart. There is a little piece still on the bottom of the rail, I cut it off and then drilled the welds after the piece was removed, this is one area that I might not be able to have access to reweld on the car.