AFtermarket or factory fender

[87 GT MUSTANG]

ok, i just wanna make a point here, i took welding in college and know all about metals, i have seen aftermarket and factory fenders and like i said they are the same kind of steel, same thickness in steel and what happens to all steel if it's not treated properly, they rust. My point being that if you buy an aftermarket or factory piece they are gonna be the same if not treated properly. I had taken off the whole front end of my car and i even matched up the good side fender to the aftermarket fender to see for myself and guess what?? they were the same, You asked for help and i gave it to you, these others guys, have they been in an accident, have they tore their car apart i don't know but what i do know is i have and like i stated b4 i WOULD NOT put a piece of **** on my car, and the aftermarket fender has been on there for three and a half years now with no incident, my car is a show car, so i would not put anything but quality on there, just because something says FORD on it doesn't meen it's quality.