Not sure what you mean by the "bridge", but if you mean "traverse inferieure sur caisse" it's 4.75 daNm.
Dear suffolkpete, the bolts that have to be tightened are these:
And if anybody have spares of these "nuts" (with metal casings - look at the picture beneath), for putting inside the chassis frame, lying around, please reply to this thread
Best,
Jesper