citroen

The BX 4x4 and 405 4x4 use a BE3 gearbox, where the differential cover is slightly different to the 4x2 model and the transfer case (TK2A for the BX and TK2A, TK2B and TK2BR for the different 405 models) is attached directly to it. The front diff is in the transfer case and in the diff housing of the gearbox is only a shaft that gets the power from the gearbox to the transfer case.

I have an extensive photo thread about the 405 4x4 transfer case (mine has the TK2B) in the Bulgarian Peugeot club's forum, section 405, thread name: "Как изглежда раздатката на 405 4x4 отвътре? Виж тук."

Giuseppe is right , the BE3 gearbox is for front wheel drive

What about the AX 4x4? Rear diff was mounted on the torsion bar suspension and the car used a standard AX shell. The whole 4x4 assembly was hung from the running gear (no mods to the shell), making it very easy to reshell a 4x4 version in a normal FWD shell if required.

The picture with the Center gearbox of the BX 4X4 is just a simple gearbox for frontwheeldrive.