It sounds like your strings.txt or shipnames.txt file is the wrong one.
GW3 uses the same strings files as OP+3.4. I reccomend you uninstall GW3, uninstall OP+3.4 then reinstall OP+3.4 and then GW3 and that should clear things up. (note there will be a new installer for GW3 soon)
Ah but wait, you say the specs are not appearing!, not the shipnames... that sounds like something else is messed up (the aastrings.txt file?) try and put in a stock copy of the aastrings.txt file and see if that puts things right. Otherwise a reinstall may be necessary (the horror!). But it sounds like you're missing or have the wrong aastrings.txt file.