Letter written on 23 Oct 1969
Osho wrote many letters to Ma Kusum Bharti and her husband Kapil, then of Ludhiana. Most were addressed to Kusum, but always mentioning Kapil too. All but a few were published in Prem Ke Swar (प्रेम के स्वर). Sannyas Wiki has images of all those published in PKS except #7, plus three unpublished letters.
This letter is dated 23rd October 1969 and was published in Prem Ke Swar (प्रेम के स्वर) as letter #8. The letterhead is a typical one of those days, showing a simple all-lower-case "acharya rajneesh" at "kamala nehru nagar" in "jabalapur (m. p.)", with his 4-digit phone number and a two-colour Jeevan Jagriti Kendra logo.
See also Letters to Kusum and Kapil