Part B of FR/N03: Chassis for N Scale TGV Duplex Motrice https://www.shapeways.com/product/UMXF4HDQM/fr-n03a-sncf-tgv-duplex-motrice-n-scale
For use with Tomytec TM-08 or TM-08R and Kato wheels (you can try other brands, but designed with Kato wheels in mind)