Two of the SAS Caravelles were sold to the Air Force in 1971, where they got the designation TP 85. The two aircraft was SE-DAG ”Dag Viking”, which got the Air Force number 85172 and SE-DAI ”Alrik Viking”, Air Force number 85210. The three last digits in the Air Force number was the same as the construction number of the aircraft.
In the beginning of their service, the Air Force Caravelles were used mostly for transports. But after two years both of them were used for their main mission - ELINT (ELectronic INTelligence). The two aircraft were modified for their new service. The nose was replaced by a nose like the SAAB Lansen. A big radome was installed under the fuselage and the aircraft was fitted with a
lot of antennas. (Text from www.avrosys.nu.)
The 85172 pictured below was photographed in 2001 at Malmen (Linköping) where it is exhibited.
Some links: 1, 2, 3, 4.