New brackets can be had by Prothane. New mounting plates are a piece of sheet steel approx 1/8" thick with two holes drilled in it.
You can buy them from "Stazi the Aussie" look in the suspension forum a few days/weeks ago for his info. $15 shipped. You then will need to have them welded in. The Prothane bracket then mounts to this new weld in plate.
Not so simple.