Lionel pre-war Shell dome car 1680. Stand alone or part of a series?

The 1680 tank car was one of the 1600 series sheet metal lithographed cars.  These were the series below the 600/2600 series cars.  Originally Ives cars, they were taken over by Lionel.

1677 Gondola

1678 Stock Car (Ives only, not made by Lionel)

1679 Box Car

1680 Tank Car (Shell or Sunoco)

1682 Caboose

These cars were upgraded before World War II with automatic couplers, so a 16xx car became a 26xx car.

Thanks CBQ.  That is exactly what I needed to know.

I should have spotted that the 1689 was a sheet metal lithograph car.  It looks so great, though, that I totally missed that.

I have looked online at the other cars in the 1600 series, and they just look a little too much "American Flyer" for me.

Mannyrock