The precinct captain for Box 13 went public in the late 70's, and admitted that he had stuffed the ballot box with votes for LBJ, on the orders of George Parr. The guy waited until everyone else involved had passed away.
More interesting is a story from someone that wrote a book about LBJ after he retired to the ranch. The author had extensive access to LBJ, and conducted many interviews at LBJ's home. In LBJ's study, there was a picture of LBJ and another man posing together. The author asked LBJ who the man was, and LBJ just smiled and said nothing.
When the precinct captain for Box 13 went public, his picture was on the news, briefly. The author recognized him -- it was the guy in the picture in LBJ's study.
thanks for the additions.