the sliders or anti friction pads? they have nothing to do with spring wrap
if your springs are OEM ? Ford may sell them ?
but many online sellers have them( use keyword Anti Friction IIRC) or you local spring shop should also
there are many sizes so measure first
if you want dissemble the whole spring clean the rust with a wire wheel and sanding disks , releive any sharp edges at the spring ends , paint, and then I use graphite paste between the springs ( it repels water and is slick as hell) then new anti friction pads /center bolt/ and u can replace bushings if need be for a better than new ride