I'm an Aviation Maintenance Technician/Avionics Technician for a major US airline. I've been in this industry for 11 years and working on airliners for 7 of those.
I have extensive experience on both aircraft types used on 9/11,doing both routine maintenance(767 overhaul for two and a half years) as well as non-routine maintenance, ie troubleshooting and repair. I've worked on pretty much every system on the 757/767.
My main areas of experience are the Electrical System, Autoflight System, Navigation System, Communications System, Indicating and Warning Systems. I also have a good bit of modification experience installing such systems as: Predictive Windshear, Enhanced Ground Proximity Warning, Inertial Reference System, Fuel Tank Transient Suppression(known as the TWA 800 mod), Passenger Entertainment, post-911 Secure Cockpit Door Modifications, as well as dozens of smaller modifications usually brought on by FAA Airworthiness Directives. Most of these modifications require a major wiring rework and installation of new wiring and equipment.
I believe my avionics background, specifically my 767 experience, qualifies me to talk about what it takes to turn a 757/767 into a drone and the major difficulties of doing so.