I see no similarity to vbulletin in the page source. They told you what it is on their forum when you asked. If you do some reading on Huddler, it was meant to replace vbulletin and phpBB forums which would explain the url mapping. There also is no recent news or mention of Huddler since about 2012 which means they are either getting updates via support from the owner of the Huddler software, doing the maintenance themselves or they are running severely dated a version. There could be some connection to the Krux DMP as all the sites I visited using huddler had blocks of krux JS code embedded.