* Correct the placement of the reserve tanks closer to the wingtips (and, in particular,
aft instead of forward of the outboard main tanks!).
* Correct the placement of the middle and aft payloads, much further aft. This makes
the 707 fly *much* better at high gross weights; in particular it is now possible to
take off with a full load of passengers and cargo. This was previously impossible
because the CoG was too far forward. Also, nose-up trim is no longer necessary on
take off.
* Add the tail as a structure that can hit the ground.
* Correct the placement of the wingtips, their lateral position was in feet but
labelled as inches (one more reason to use the metric system!)
