Remember, if you have two models for a turret (such as a turret body and a gun-barrel) you need to glue a light (as a sibling) to the associated rotational submodel (usually the gunbarrel) and then glue it to the main part of the turret as a child. Once all that is done, glue the whole assembly to the hull as a child.
This is the procedure I worked out for Truespace 3.1, I don't know if its different for other versions of truespace.
Another tip on turrets, you may only have dorsal and ventral turret positions rotate. I'm currently working on a project to try and trick FS1 into accepting flank mounted turrets but I haven't had much success yet. If you must use flanking turrets, do not use them as rotating objects or you'll get weird results.
Hope this helps...
