People have reported sightings of a non-syncro Vanagon with a syncro
fuel tank system added, though I do not know if anyone one the list has
one. The dead giveaway is two factory looking gas fillers, one up front
below the passenger door, the other over the rear wheel.

Another option is to put a long skinny saddle tank outside the frame and
inside the rocker below the rear door area. This is similar to what
Bob Hoover did with his splittie.

Tom F.