The locomotives are fitted with monomotor bogies with two different gear ratios.

This allows them to increase their tractive effort in exchange for a reduction in their top speed.

[5] They were built in three distinct batches, leading to detail differences.

Thirty locomotives, dedicated to empty stock moves, have been reclassified as BB 88500.

[2] Likewise in 2001, 20 of the class were rebuilt for freight banking workings on the Maurienne line.