I've even called Ruger to inquire about the grip frame screws between the Wrangler(s) and the Super Six. They said they won't work. WRONG!!!
The screws will interchange between the pistols (as long as it's the New Model SS). Only difference is the nicer torx screws the Wrangler's use, but they don't (nor can get) them in stainless.
Will the torx-head screws work in an Old Model as long as you get two of the shorter upper screws. The OM doesn't need the extended tip that's required on the New Models.