Fisher plows use a different trip spring assembly than any other plow on the market. Most trip springs mount on the top of the plow but Fisher has them mounted on the bottom. Our replacement trip springs can be purchased by the piece or complete assembly. The complete trip spring assembly includes the spring bar, bolt and nut assembly and, of course, the spring. Our part number for the complete assembly is 315-9123 and it replaces the manufacturer number A3770. All parts are available separate.