I discovered a bit of surface rust (see pictures) I used my grider with a scotchbrite disc to remove it. I hit it and the top surface rust comes off but the darker rust will not come off. The surface is completely smooth with these dark stains underneath. The metal seems solid. Questions is...Is it ok to use this fender? Any ideas? I would hate to paint and have problems down the road. I am also afraid of the fitment of new fenders.

Thanks

Bob

http://www.valleydentalsupply.com/bobf/fender1.jpg
http://www.valleydentalsupply.com/bobf/fender2.jpg

i had a fender in similiar shape.
i used a d/a with 80 grit and got almost all of it off.

From the pics. it appears to have pits in it. I suggest you have it glass beaded or meadia blasted.

Blasting with an abrasive media would be the quickest and easiest way to remove the discoloration. You could also have the fender dipped if there is a shop that does that nearby.