If we're going to do wound and assassination-photo recreation, we need reasonably accurate models. Mine aren't there and may never be. I've hit a technology ceiling with my computer.Meanwhile, soak it up with Cartoon Ernie and his Hum3D model. ( Link )
The top of the jump-seat-back is several inches below Connally's armpit area and so did not interfere with the bullet path.See where the top of Nellie's seat-back is in the above photo; it can be seen in the side-window of the parade bar. The Governor's seat-back is the same height.