I was trying to find one specifically for 2.0.18, but haven't been able to locate a free one. This one does have recent posts so I am assuming it is compatible. As always, make a backup prior to using the hack as I have not personally tested it. I have had Phpbb SEO on my list for a while, but I recently purchased a license to vBulletin so I have been messing around with it instead. If you do find something that works let us know what and how it turns out.