For this history, the telecom GSM-R measurement car located between the two Class BB69400's is called "Helene 184" or "LN184". She is one of the two prototypes of the model Eurofima coache. She has now belonged to SNCF Réseau for a few years, but the interior (doors, windows, curtains, carpet, etc.) is still vintage! The second prototype called LUCIE serve to testing track circuits but also the traction return current with the VULCAIN measurement wagon. You can see this car with this wagon on this picture : https://trainspo.com/photo/115473/
. These are still the only two in circulation in France.