Went to my new servicing dealer today and took the shop foreman for a ride and discussed all of the issues with the truck... Guess What... HE AGREED WITH ME!!!!!
He even admitted that they currently have a few other pick-ups there for the exact same problems and that he has personally helped a good number of other people fight to get a buy back. He and I discussed all of the different scenarios make the vibration worse such as going around a curve, up a hill, temperature differences etc. We also discussed different parts and what we believe the root cause to be, he actually said that he believes that the frames on the trucks are not 100% true, and that the truck is fighting the frame while driving, in addition to the stiffer frame and changed material for the mounts causing all of the resonances to be transferred into the vehicle, he actually called the truck a "tuning fork" lol.
According to him, I definitely have the T1 Vibe, possibly a T3 and Prop... hopefully I am remembering this right... I was also able to get him to listen to the issues I have with my radio as well, again he agreed that the radio definitely has problems. However he said hes NEVER seen, let alone heard of the problem I have, where it will randomly lose all of the highs in the audio and fade, the only issue he has seen was with the reception and HD Tuning, and my truck doesn't have HD.
Anyway, they are going to call me when they get a loaner vehicle back, to so they can schedule it for me, they will be taking my truck in either this Monday, or next Monday, I am also going to bring my 18" wheels with me so they can run the Picoscope on those aswell, even though I have had every intention of switching the tire to something that is better for A/T... yes I am still arguing with them about paying for and not receiving A/T tires...
Now the kicker for anyone with a '14... The foreman told me that when GM ordered the rear ends from American Axle, it was a late order, so AA started just cranking them with little quality control, he then went on to say that they never changed the tool kits when manufacturing them... the tolerances turned to sh*t, and the more they produced, the worse they got... So anyone with a '14.... that could be part of your problem, he was telling me about one truck they had , it registered 56 on the Pico, GM somehow determined that 22 was the threshold. they overhauled the original rear end, then ended up replacing the entire assembly. They obviously did not fix that truck and it was one of the buy backs that he helped with.
I asked him if he knew how GM came up with the 22 spec for the reading on the Pico, because that is still a felt vibration, and quite honestly for the amount that we pay for these trucks, any vibration like this is bullsh*t. he said he didn't know where GM came up with that spec, but agreed that if he was a consumer and had purchased one, he'd feel the same way.