This is a quick conversion made from a Jada Badge City Police Bus.  It is a pretty simple conversion that I did over the course of an evening while working on other projects.

Large or heavy cardboard packages will often have fiberglass bands that are used to hold the box together during shipping.  I keep a few pieces of this in my bits box because the texture makes for great metal plate.  As it turns out, the texture matches the texture used on the bus windows.  I cut four pieces that match the sizes of the front and side windows.  These got black primer and a drybrush of metal.

I took the bus apart to prime and repaint the plastic parts. I like to get rid of the chrome that is way too bright for a post-apocalyptic setting.  While I had it apart, I put a magnet in the top so I could attach a removable turret.  The turret came from the Warlands Rattler Gun Truck.  It got a white and black paint scheme to match the rest of the bus.

Once everything was reassembled, I touched up some of the details that were missed by the factory, then weathered everything.  I added rust colored wash, splattered it with mud and metallic scrapes, and finished with a brushing of a sand color.