LS400inNC

How do I replace one of the tail lights? It's not one of the bulbs that is inside the lifting portion of the trunk, but rather on the corner of the vehicle. I pulled on the housing and it pops out, but seems to be secured by something else towards the front of this housing. Just purchased this vehicle and don't know how to replace these bulbs. Any help is greatly appreciated. Thanks. Sorry for the typo... this is actually a 1994, NOT a 1995 if that matters any........