Thanks Ian
Will be interesting to see what you come up with in your research.
Whilst on the subject of decals here, I'll put up this pic of a rare black wheeled M8a tanker that I recently acquired.
Its sporting Esso decals though I don't believe that they are original to the model, as I have never seen them on another.
Perhaps you may have some idea on this one as well, as to where they may have come from. They seem to fit the tanker very nicely.

zBret