These are the speakers I ordered;
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Inexpensive but far better than the OEM. All we do is watch movies from time to time so buying speakers that are an audiophile's dream wasn't important. They went right in the existing holes. I didn't put anything behind the ceiling and they've been in place for 3 years. You could try to use the speednuts shown above but I'm not sure how you would place them over the tip of the screw with the speaker in the hole.