Looks like the rust is on a "button" inserted in the bumper. The actual bumper bolts cannot be seen when looking at the outside of the bumper. Buttons are used to fill in a damaged pit, or an unused hole from a previously mounted light, etc. As mentioned above, these bumpers had no buttons originally.
Can get at ground level or remove the bumper to check the inside and do any cleaning needed...can get new buttons. The bumper itself does not seem to have any rust.
The bumper comes off by removing two 17mm bolts that attach each half of the bumper to the bracket. There is a center cover held on with a few small bolts. The bumper is attached to a black bracket that is bolted to the car.
The inside of the bumpers came with protective off-white paint. Can clean the inside then apply a light color Rustoleum or similar. If the final color is not correct, can use rust proof cream color spray-on paint for propane tanks. This will give the correct look and some additional protection.
If that's all the rust you have, Be Happy
Richard M, NYC
