vibration at 25-40 mph

If the trans is 2 degrees down you want the pinion yoke up 2 degrees or close to it. Vice versa also works with trans up and pinion yoke down, they need to be opposite and equal. Make sure you check it with load on the suspension, not up in the air with an unloaded suspension. I've broken a driveshaft on the track, tearing up the trans in the process, because of an incorrect pinion angle.