Gentlemen! Is everyone forgetting that as the wheel and spindle move up and down, through their normal travel as suspension parts, they describe a curved arc, which means that, since the differential center section is rigidly fastened to the frame, the axle shaft tries to in effect get "longer and shorter". For that reason, one C-V joint on each axle is specially made to slide in and out, to compensate for the curved travel of the wheel.
The C-V thus made to do this is usually the inboard joint. This is analogous to the driveshaft slip-joint which for years in vehicles with solid rear axles has compensated for the fact that the differential center section moves forward and backward a little bit as suspension moves up and down. imp