Can you describe the pinion shaft in the rear end that has to be lowered to slightly push in axles to release c pin?

Can you describe the pinion shaft in the rear end that has to be lowered to slightly push in axles to release c pin?
is this in a gm vehicle?if it is , it is not the pinion shaft that needs to be lowered.it is a square block , held in place with one bolt, inside the diff housing. this block holds end of axles apart. when this block is removed, you can then push axle shafts towards centre of vehicle to remove c-clip that prevents axle from sliding out of diff and axle housing.any good shop manuel will have a picture of this