I have a couple of signs hanging in the Mustang cave. The Goodyear sign is my favorite and actually a bit of a mystery. Here's the info I have: 

It's 100 inches long and made of solid brass with blue enamel lettering. I bought it in 2005 at an auction here in Denmark. I asked the seller where it came from and he told me he found it in 1988 while digging in his garden. He was curious to know how a thing like that could end up in his garden.  It turned out that until the 1940's the area was used as a junkyard. It's still strange though how a sign like that could end up in Denmark. Some think it's a sign from a merchant ship and that the ship ended its days here but I doubt that.

Goodyear Tire & Rubber Company was founded in 1898, so maybe the sign is from a time before then. Perhaps from Charles Goodyear's earlier years (google his name and check his history - tough life). When I google the exact words "Goodyear Rubber Co. New York", not much more than an add from 1884 in an old paper pops up. http://chroniclingamerica.loc.gov/lccn/sn90059522/1886-05-06/ed-1/seq-2/ 

Some years ago I asked the American Sign Museum, Goodyear Tire & Rubber Co., and some US vintage sign sites, but none of them were able to tell me its age, or where it could have been used. If anyone has any information on it, please let me know.