Thanks Charlie - I've looked at a lot of Renault photos, but don't think I'd come across any of that before. It initially looked like they'd taken a FT body and placed it on another chassis. I queried Meng on shipping of their FT a few days ago, and mentioned many modelers were hoping they would introduce contemporary kits of other WW1 tanks.
Checking images of Renault NCs - the exhaust normally seems to be parallel to the top run of the track. Perhaps this was a local modification to reduce the amount of
exhaust gas being sucked into the engine compartment.