@PhilipShaunTaylor, yes you will install this on all 3. The HF version will need a inputs.conf (and outputs.conf) if one is already not setup. You can turn the UI off for the App if you do not want to see it on the left bar. Same can be done for the Index/er's which will use props/transforms. The Search Head/s will utilize the savedsearches/tags/eventtypes.