Original: In late 1978 a placard containing instructions on how to lower the aft stairs of a 727 , later confirmed to be from the rear stairway of the plane from which Cooper jumped , was found just a few flying minutes north of Cooper 's projected drop zone .
Simplified: In late 1978 , a placard , which contained instructions on how to lower the rear stairs of a 727 was found just a few flying minutes north of Cooper 's projected drop zone .