Early 9N owners/restorers looking to complete their projects with the correct decals for their Donaldson air cleaners can get them at a place called OK Tractor.com –see link below. Donaldson air cleaners were used on Allis-Chalmers Models B and C tractors and probably others as well, but this place sells the whole decal kit -they are an Allis-Chalmers supplier, so you will have to get the entire set just for the two yellow air cleaner decals as used on the early 9N Donaldson air cleaners. In the famous photo shown from that day in June, 1939, with Henry Ford in the tractor seat with his straw hat, and a young David McLaren getting ready to switch places and show the media that a young lad can plow just as good as a seasoned pro, you can see the Donaldson air cleaner and the proper location to apply the decals. Now these were only used on the Donaldson air cleaners so if you have a United air cleaner, the standard blue ones are correct. Thanks to Steve Dabrowski for finding this information and sharing. Early 9N Tractor guru Kelly Jewell also sells just the two yellow decals for a low price but the clarity of the OK kit ones are much better. I’m not disrespecting Kelly in any way; see his decals in scan below. They are good quality and will work fine. Kelly’s are vinyl adhesive and OK’s are water soluble –just like the originals.
OK Tractor Part Number: MHA110 -complete Allis-Chalmers set
Kelly Jewells' Repop Decals-