[otrs] Need to backup all data from a system to restore in another

Hello, I have a client that has otrs which I don't know the version, probably 3.0.4, all I see is ITSM 3.0.5, I need make a backup of the data, I did a dump of the database, I need to recover at first only the ticket information, which tables I need to recover? Is there any database difference from otrs 3.0.4 to 3.0.11? or how can I be sure that is 3.0.4? Is there a chance of breaking the database doing a recover from different versions of otrs like that? I don´t want to upgrade the currently otrs as there are a lot of customizations that a different company made and has no documentation, so I'm almost sure that upgrading otrs will break most of it. Thanks