The hybrids I see below the dam on Livingston, I believe are primarily naturally ocurring Sunshine bass. They are a relatively dark color. TP&W annually removes female brood stripers from the basin leaving a predominance of male stripers which then cross with the abundant female white bass. See attached picture of two hybrids caught below the dam last week(larger fish just over 10 pounds)
On the other hand, the hybrids above the dam on the main lake and in the river are primarily Palmetto hybrids, IMO, and are the result of fish escaping from RC or other places into the Trinity River. They are primarily not the result of natural spawn, but escapes from TP&W stocking programs in the Dallas area. Look at the recent photo of what I believe to be a Palmetto hybrid posted by Megafish yesterday to compare.
Just my opinion.
The hybrids in both locations are a blast to catch and like Sunbeam, I wish we had millions of them in the lake.