Only SM is applicable for Direct Tax May 2018:
This Announcement is Relevant for May 2018 and Nov 2018 for both DT and IDT Papers.
The new Study Materials for Direct Tax Paper under the the NEW Syllabus is applicable for Old CA Final Course as well, with the exception of the following three topics from Int Tax:
Ch-6: Overview of Model Tax Conventions;
Ch-7: Application and Interpretation of Tax Treaties; and
Ch-8: Fundamentals of Base Erosion and Profit Shifting.
Since the Study Materials are all inclusive, there would be no separate Practice Manual, Supplementary Study Paper or Select Cases for this subject.
To conclude, for DT Paper, you just have to refer only the new SM.