Excellent!
That’s the first concrete lead I’ve heard 
And also, @OtherMichael , I recall the baby food jars and the later switch to toothpaste tubes, so I think the movie may have been relatively faithful to the book.
Edit to add:
Well, damn… 
Now that I look at the link to the book, I see the protagonist was black, which was changed (as I recall) in the movie. At some level, I’m not surprised, but I’m retroactively disappointed.
On a happier note, I read The Great Pushcart War with great pleasure, so I have every confidence the book will be far superior to the movie.
