Most plating shops will do everything but cleaning the grease off them. They will strip the rust and cad plate bolts, nuts in lots. I took 2 lb coffee cans of them into my local plating shop and they were done for $25 per can full. Of this, you'll get about 80-90% usable body bolts, brackets, etc. Do not use this process for high tensile strength fasteners in grades 5 or 8. Its best to replace grade 5 and grade 8 fasteners if they are corroded.