My buddy found some (used) shafts here, so thank you for the offer but we will try these first.
In my opinion, the axle shaft can freely move in and out. On the dif.side this movement is stopped by the cross shaft (top is rubbing), the c-clip prevent the shafts of moving out too much.
With some wear, this movement will increase and the axle can move more inward (not outward, the c-clip NR 33 keeps preventing that)
Will try and make some pictures when we exchange the shafts (have to open the diff to remove the c-clip)