I just did a re-encode of the 3D SBS Trailer 3. The new encode is half side-by-side 1920 x 804 and should playback nicely for those who had problems with the full 3840 x 1080 version. It took me a while to figure out how to get the file resized correctly. In the end, I used handbrake to set the out put to be 1920 x 1080 anamorphic = none. That almost worked, but it was too stretched vertically. So I went with 1920 x 804 which matches the resolution of the 2D trailer. I then used MKVToolNix to remux the video with the audio from the Full SBS. I hope that does the trick. It is listed on The Force Awakens page as “Trailer 3 3D HALF SBS 1920×804”
If you do not have the Original Trilogy on Blu-ray the new steel book editions are now available, and for a pretty good price.