RE: strange DC-3

Looks to me like this aircraft is used for geophysical survey work. There is lots of mineral exploration these days in Brazil, and airborne surveys are a key tool in that work. Sensors are used to measure various things. For example, the tail boom is likely used to measure magnetic anomalies, using technology much like that used in coastal patrol aircraft like the Orion or Nimrod. Not really sure what the others would be for, but as a geologist, that’s my educated guess.