Ron,
I agree reference the pod distraction although we disagree on it's significance. I admit it would have been possible to have a 767 RPV, but I see no actual evidence of that. The "pod" is not required for the aircraft to become an RPV; all the necessary mods would be internal. Any large additional electronics could be mounted in the cabin area.
The USAF has been converting their superseded fighters to drones for some time. They normally use them for missile practice. Here is an image of one:

Can you see any pods or otherwise distinguishing it as a QF-4? The bulges on the spine are normal for the aircraft - not a drone mod. The aircraft looks exactly the same as a regular F-4. The two giveaways are:
- DayGlo orange on the wingtips and extremities; and
- No crew in the cockpits!
(Actually, I suspect there may be a small aerial somewhere underneath or possibly near the tail, replacing one of the regular UHF antennas. If you were very intimate with the particular version, you might notice)
So to my way of thinking, if you did substitute a drone aircraft for the real flight, you'd have to make sure that the drone was indistinguishable from a regular 767. The presence of a pod goes against this (different from the regular aircraft), and would not be required for a drone. A pod defeats the purpose of the drone.
Some have said it contained some type of missile. Why have a missile? Oh, to create that hole in the building.
But again - why? In case the aircraft missed? That's silly; if the aircraft missed hitting the building, then having a missile explode on the building would be HIGHLY suspicious.
To make a hole for the aircraft? Again, not backed up by facts. An aircraft hitting the building would contain FAR more energy than anything less than a bloody huge missile; far larger than could even be hoped to be concealed. It would be painfully obvious that it was an external store, and once again defeats the purpose of pretending to be a regular 767.
Plain and simple - it does not fit. The pod is a fantasy. It is explained by the light, shadow, aspect, film quality, etc. Trying to explain a pod on the aircraft, associated with some nefarious 9/11 plan, immediately defeats it's own existence!