I remember TDB very well at Jandakot. I was an apprentice engineer with Simpson Aviation there and we looked after TDB in 1969 / 70. I had my very first flight in this aircraft - hence my memory of it. The flight was to calibrate the autopilot servos I think. I remember having to do an engine change on this aircraft too. Yes, it was fitted with a floor mounted camera mounting and very expensive glass lenses arrangement for the internally mounted camera to "see" through. The engines are not for the faint hearted. Very expensive then, eye watering so now I would think. They had a lovely turbo sound on power but, at idle it was another matter. The straight cut spur gearing for the prop would make horrible mechanical clunking noises due to the gear backlash and the rougher idling engine. Once under power however the backlash was all taken up and there was no gear sound. As Mach E notes above - there was another 411 in WA too operated by Bell Bros - an earth moving contractor at the time and later to become a famous Alan Bond aquision - I think it was registered BBV.