[RyanAK]

Vibration... ugh.

Wheels and tires greatly lessened but didn’t eliminate the vibration at 45-55mph. It moved appropriately with the change in tire size and now seems to modulate a bit. The new tires are quieter, so now I’m hearing some sounds I hadn’t heard before. I think the exhaust is certainly a component. The vibration is now more sound than feel. Haven’t had it up to interstate speeds yet, so don’t know if the rumble at 65-70mph is any different.

The front driveshaft double-cardan CV joint is high on my list of suspects... along with both driveshafts’ balance. I replaced all the other driveshaft U-joints. This is my first experience with the full-time NP203, so what is “normal” is still a bit of a mystery. There seems to be a little bit of a whine at low speeds. Maybe the transfer case and the differentials need a look... Dropping the front shaft is probably a good idea.

(Somewhere in my mind I’m still contemplating a part-time conversion or swap, but I’m hoping to stay stock NP203.)

Other things running through my head: Can rear suspension sag change the pinion angle enough to be an issue? Wheel bearings? (Never had a bad one, so not sure how to diagnose...) Brake drums or rotors? Torque converter? Fan? Exhaust resonance? Worn out suspension bushings? Front axle u-joints? Alignment? (Front axle actually appears as if it isn’t perfectly centered under the body/fame, though the truck handles fine...)

I’m 85% of the way to having this rig running down the highway almost as smoothly as my 2011 Z71 Tahoe. I’ll get it eventually... just hope I solve the remaining niggles before I end up completely rebuilding the drivetrain and suspension! I’m super happy with this truck.

Appreciate the interest, suggestions and encouragement, fellas.