Is this the only ZiU 682 that has been exported to Argentina?

Definitely not, all three Argentinian systems had purchased ZiU-682 trolleys in the past - see the database for details. However, they remain in service only in Cordoba, and this unit was the only 2-axle ZiU in revenue service that day. Few other runs were operated by new low-floor Trolzas, while majority of route C was unfortunately dieselized.