who's in the truck?

So now there's a suggestion that it should be "who's in the truck" rather than "what's in the truck".
    It's based on a message from Dreamworld received last night by CBA, who dreamt that she and I and Warren Zevon and a movie star to remain nameless were caravanning cross-country with three semis full of stuff (must say it feels like it sometimes) and the Amazing Growing Salt-or-Freshwater Fish! Sounds like a traveling circus, which it ofttimes is. Then she located this riff she had never heard before by Warren Zevon about why he needs a truck—or several.