It would of been best to post what this cable was actually for, than to just post a part number. Without looking up the part number through parts diagrams, no one knows what your talking about.
Now to get to it. That spring is not available separately from the cable. The spring comes with a new cable as an assembly. If you only need the spring, then you either buy complete cable, make up a spring yourself.....or remove the cable altogether. Because that cable is only a reverse lockout cable, most remove or bypass those cables so they can select reverse without using the foot brake.