One of the four trial locomotives on the Mont Cenis line was the 161 AE 1, supplied by Schneider and Alsthom. It shared the total number of eight axles with the 242 BE 1 and 242 AE 1, but the body was divided into two parts, as with the 242 CE 1. In contrast to all the others, however, six axles were powered and only two axles were used as carrying axles. This was realized by mount each half of the locomotive on two bogies, of which the outer one consisted of a carrying and a driving axle. The power came from axle-mounted motors with spring-loaded gears that allowed 110 km/h. It was later reclassified as 1ABBA1 3500 and remained in service until 1967.
The 161 AE 1 was the only one of the four locomotives from trial operation that was reordered in a total of ten units as a direct development. The production locomotives were designated differently as 161 BE, since they were intended for use in front of freight trains. In return, they got simple axle-mounted motors without spring-loaded gears and a different gear ratio, which only allowed a maximum speed of 80 km/h. The hourly and continuous output was increased by 90 and 110 kW, respectively, and the weight also increased. The SNCF used the locomotives until 1973 and named them 1ABBA1 3601 to 3610.
