In about 1984, the Joint Stock 'Overland' Twinette berth cars were split into two groups: JTA and JTB_. The difference in classes is the age of the cars; older cars were reclassed to JTA.
JTA 1 to 6 were from cars Nomuldi, Mokai, Malkari, Paiti, Yanni and Kuldalai respecively.
These cars were 20 berth sleeping cars and had a mass of 49 tonnes.