2005 Chrysler 300C
72,000 miles. Vibration problem, acts just like classic U-joint wearing out on older simple driveshafts. Problem first manifested at about 68,000 miles on return leg of 2000 mile trip at 70-80 MPH. Worse at neutral and trailing throttle.
Worse but higher frequency at higher vehicle speeds. I can isolate engine
by shifting to lower gear and have same vibration at same car speeds, so i believe it isn't the engine, flex plate, torque converter, or input side of trans. I have a lift and extensive
tools. I removed driveshaft and sent it to specialty shop. I notified them that the slip splines in the middle were loose enough to make a "clunk" sound when I manipulate. They returned that there was .0018 runout in the rear shaft which they corrected, replaced
both biscuits, but the slip spline was "within spec". I then took to dealership who said they felt no vibration. I returned to dealership and service manager rode me, I point out the mirror shuddering etc and he agreed there was vibration but thought I needed
a "road force balance" on my tires. As my (michelin) tires were due for replacement I replaced all four along with a wheel that my tire shop said had small runout...no change in vibration. So what do I do next?