If the Digest of CBDT Notifications, Circulars and Instructions software doesn't contain CBDT Instruction No. 1739 dated 19-12-1986, I recommend you use Google search engine in order to find a copy. Also, you can contact directly the developers of Digest of CBDT Notifications, Circulars and Instructions program and ask if they can't provide you a copy of the document. You can get in touch with them using the contact information from the official web page.