[svxAL]

What u need to do is determine how bad the rust is. If it is bad aka rusted threw or bubbling on the inside) your going to need to cut it it out and weld a new panel/piece in. ootherwise grind it to get rid of the crack and or rust in this case grind till there is bare clean metal. Then re fill it using some evercoat filler. feather it out and prime it, then block it out , then scuff the whole quarter with gray or red scotch brite then paint it. done deal.. and dont worry if i had bady work done/ has filler in it I put filler in cars with 5 10 miles on them all the time at the dealer I work at. Just save that baby before she gets worse.. let me know if u have any ? and ill be sure to answer them!