When referring to the 'Cardan Shaft' on a DMU it commonly indicated the second shaft that connects the transmission to the final drive. However is is just one of several fitted, each is dealt with here.
The drive from the engine / fluid coupling to the driving axle was transmitted by means of two propeller shafts as follows:
The first shaft incorporated the freewheel mechanism and, on early cars, was fitted with two types of universal joint, the one at the engine end being of the plain bearing type, the other end being the needle roller bearing type. On later cars both universal joints were of the needle roller type.
The second shaft had a sliding universal joint at one end and both joints were of the needle roller bearing type.
On early cars the drive from the engine to the radiator fan was via two shafts as follows:
First shaft from the engine to the relay bracket
Second shaft from the relay bracket to the fan
On late cars only one shaft was fitted between the right angle fan drive and the fan.
All shafts between the engine and the fan have a sliding universal joint at one end, the joints being of the needle roller bearing type.
The dimensions and types of the cardan shafts used can be found here.