Recovered history: Top kennedy military aide says lbj was badly shaken after assassination

[Charles Drago]

In Craig Roberts' Kill Zone: A Sniper Looks at Dealey Plaza the author prints two page-size diagrams of the aircraft type of tail number 26000, Air Force One in that era.

Roberts shows a floor hatch from the compartment where the casket was, to the rear cargo compartment with its hatch on the right side.

If memory serves, it was at a Lancer conference in Dallas that a presenter attempted to debunk Lifton by presenting a video taken aboard the Kennedy 707 in its then-current, open-to-the-public location. In it he demonstrated that there is no hatch that opens beneath the fuselage.

Which might have been a clever act of mis-direction.