Photos courtesy of Lonny Beno

These signs were never cataloged, but we can probably date them from the train sets depicted on them. 

The upper sign appears to be a stylized version of the 4615 set which was offered from 1946-1949, with perhaps an added car at the end.  This sign is most likely from that same time period.

The lower sign is clearly a depiction of the 5110 set, offered in 1951, or K5210 set, offered in 1952, so it is safe to assume that this sign is from 1951-1952.  Since very little was made available free of charge, I assume these signs were also sold to Authorized Dealers, much like the other signs. 

I understand that the only thing the Authorized Service Center operators got for free was a decal to identify them as such.  A framed version of that decal is shown at the left.