There should be no questions about the authenticity of your signs. All three you had listed are/were without question the real deal. The thing about the two with the thin blue borders is they are from the Magnolia marketing territory and the design is unique to that market. For some reason they get questioned, especially by newer collectors unaware of this fact. The diesel is the standard Mobilfuel Diesel sign. These are normally dated 1951, 52, or 53 with the wide blue border.
If you needed any 2nd opinion on authenticity I just gave it, lol!