Let's see. Pre-TRS2004 locos have no visible driver since they were not allowed to show that feature. TRS2004 was revolutionary on this too. It put forward the possibility of adding two (or more) attachment points a.driver0 and a.driver1 (front and back) to automatically associate a built-in driver to the loco in a ssession (or manually if you wish by handling the rule in Surveyor).
So, unless you have access to the original mesh to add those helpers (attachments points) no visible driver is going to appear on your locos.
Initially, Interiors have nothing to do with drivers, but you could build an interior with a driver figure included. But this wouldn't be seen from the outside of the loco. The problem is always the same, if you don't have a mesh file, nothing can be done except trying the 'kind attachment' system (if you build a suitable mesh or use a Mr. Driver by Jack Straessler) figure on the DS or from the ones included the Auran's Content Creation Art Source CD's. Check the Content Creators Guide, please.
Attaching a mesh to the default mesh using the kind attachment effect.