Letter written on ?? Jul 1957
From 1957 to 1963, Osho wrote many letters to Babulal Ji Deriya, of Babai (MP), India. The wiki has images of thirteen, believed for now to be all of them. Most are written on postcards. See Deriya Ji's page or Osho's manuscript letters for links to all these letters.
For the Post Office, Osho used his full name as above. In addressing him personally, he wrote "Poojya Deriya Ji" or "Shraddheya Deriya Ji" (venerable, honoured), only later using the more familiar "Priya Deriya Ji" (dear, beloved), but all following his sometime custom of addressing male friends by their last names. See also Lashkariji, Punglia Ji, etc.
This letter is undated and sent from Sagar, where Osho had gone for his graduate studies. He wrote it on the letterhead of one of his most-loved professors there, SK Saksena. An English translation was published in Sw Ageh Bharti's book Beloved Osho, and likely the Hindi original version was published previously in one of Ageh's Hindi books. It is said also to be in line to be published eventually in a larger edition of Prem Ke Swar (प्रेम के स्वर) (as letter #57), though this development appears not to be fast-tracked.
An approximate date has been estimated from the text in the letter: Osho asks if Deriya Ji has received a letter he wrote from Gadarwara, saying he has just come from there. He is referring almost certainly to the Letter written on 5 Jul 1957, wherein he had talked about wanting to get together with Deriya Ji and going next to Sagar.
This letter has a lot of detail about trying to arrange a job, especially a possible professorship with the help of Deriya Ji and Seth Bhagwandas, among others. The translation from Ageh's book is reproduced on Deriya Ji's page.