Since GeoNet links to all versions prior to 10.3 do not currently work, I've been trying to use links to the 10.3 help in my recent replies. My method is no surprise: type it in Google, go to the result.
Why is it so difficult to find 10.3 Help pages through a search engine? Is there some reason the 10.3 help pages have not been indexed?
Try it for yourself. "arcgis 10.3 spatial join" returns all versions of the spatial join tool help pages except 10.3, plus the home page for 10.3 help. Are individual 10.3 help pages not searchable from outside the help pages?