It could be an HZ chassis with a WB cab fitted. If all the plates were transferred, then all of the numbers would still match !

There are many small differences between WB & HZ, much of it to do with wiring.

Does the plug at the base of the column match the blinker switch wiring ?

Where the ignition coil wiring is at the firewall, is the coil wire a skinny yellow one or a thick pink one ?

Dr Terry.