I don’t believe any 1940 Fantasound prints exist. The Fantasound mix was supposedly already deteriorating even in the 50s, which is why they backed it up by running it from the studio to RCA over a direct phone line.

Disney has certainly never been able to locate any original Fantasound elements. They replaced Deems Taylor’s voice because they only had usable picture elements for the roadshow scenes, not sound. (This leads me to assume the Fantasound source used in the phone transfer was the general-release edit?)

And I’ve heard stories from two knowledgeable sources that most/all of Disney’s backup positive elements were junked - during the early years of the Eisner regime? - either out of nitrate storage concerns, or a belief that they were redundant and useless because all the negatives existed. I am not sure if any Fantasound copies of Fantasia were trashed, or if they were all already gone.