There are incidents and code names described on the newly discovered two-plus hour recording. It predates a shorter recording formerly thought to be the only surviving version.
The Raab Collection, a Philadelphia historic documents dealer, is selling the reel-to-reel tape for $500,000.
The tape comes from the estate of Army Gen. Chester "Ted" Clifton Jr., a Kennedy aide who was in the Dallas motorcade when the president was assassinated.
Clifton died in 1991. The Raab Collection acquired the items after the death of Clifton's wife in 2009.