Possible Fix for Slight Vibration above 50 mph
 

I have had a minor vibration above 50 or so mph(by speedometer).

Installed a new driveshaft and corrected the pinion angle to near perfect. It seemed to help a little.

I have OEM 4.30 gears and 33.4" tall tires.

I had to retune motor/PCM and one of the options while installing the new tune was tire revs per mile. I input 620 and pressed on.

Now my slight vibration is gone. Even at a corrected 70 mph it's smooth.

I'm a little baffled, as I do not understand how a tire diameter correction in the PCM could affect the drivetrain?

Any suggestions?

Pcm could be using that value for abs system causing a brake issue to cause the vibration? Someone with a deeper understanding of the X will have to chime in

I had a similar issue with a Sub I owned for years. When I replaced the U Joints, I checked the rear yoke. I gave it a good solid tug. And moved it side to side. It had vibrated a little bit loose.

Torqued it back to spec and the vibration disappeared. So if this comes back, check your rear yoke to make sure it's not loose, even a little bit. I can not say whether the U joint wearing out caused the yoke to loosen or vice versa. But there is another possible cause for vibrations in the drive line.

I don't think it did but change the revs/mile back to what it was and report what changes (if anything).

^^^^ What he said. I've been fighting a vibration for months...

I had the same issue and it was my rear ujoint. Since you replaced the driveshaft maybe get it checked for balance instead of chasing ghosts.