Big John's Salvage It's actually two cars that form the gate there, but pretty close. Then it's just a matter of adding lights. All of this is beyond me, but there's at least a model for it in the game.
There's a super-mutant encampment, in a junkyard, that has a gate made from a truck or a bus, I can't remember which. Can't remember where I found it, either, just that it was a nice touch.