Similar to what Mick said for all my stuff whether scrap or other stuff...
-Post on craiglist for fair price
-Drop price every few days until it get's to scrap value
-Scrap it or take to Goodwill if it's not scrapable

Try some other sections of Clist like Autoparts(floorpan or other sheetmetal work on car), Materials(you probably have it there), General, RV(trailer repair), Farm and Garden. Sit down with a pen and paper and brain storm a list of keywords and put them at the bottom of all the adds you post.