driveshaft angles

He's not listening because you guys are wrong. If both front and rear yoke angles are down; you'll have a vibration unless the axle is twisted upwards in the front; under acceleration; at which time the yokes would be parallel, but just at a crusiing speed, the yokes are not parallel. Listening?
No, you're not listening or understanding, but then, no one can tell you a damn thing, because you already know it all.