'21 5.0SC Westminster 30K miles. High frequency vibration felt at ~45mph and more prevalently at 75 mph+. Intensity is not effected by rpm, gear, +/- load rather only speed. This seems to narrow it down to tranny output shaft, driveshafts, joints and carrier bearing. Upon visual inspection, driveshafts are spinning true (no wobble), output shaft, carrier and joints have no play.
The only things spinning fast enough to create this vibration frequency are the driveshafts. Might one be out of balance or have lost a weight? How common is this with such low miles?