IIRC this was dropped because it was not consistently signed. The only GMSV along the route is from 2009 - goodness, Google, can't you drive through the oldest places once more in hi-def? - and that sign you found is the only one I see. It's not signed at the WI 77 intersection at all from what I can tell.
If there's a clamor to bring it back, I still have the file.