Stories used to go around Democrat circles in Texas that LBJ swung the dead vote for Kennedy in 1960. Dead people in south Texas, duval County, voted and they did it in alphabetical order. Funny old Demo story. LBJ did steal more than one election in Texas.
There is no proof for that whatsoever.
It is also highly unlikely that vote fraud could account for more than 1 out of every 50 votes statewide. Not to mention that assumes there was absolutely no Republican fraud at all (a naive and/or partisan assumption).