clunk/jerk/metal-on-metal

From reviewing years of complaints about this same problem, it remains "NOT ADDRESSED" by GM/Chevrolet. Service departments know the problem, as it has been explained as "CLUNK" and "LAG" or other that I don't recall at the moment. I was told at one GM Dealer Service Department that a "Bulletin" has been release by GM on the problem. Chevrolet service can not or will not replace anything to correct the problem. The frequency of this problem's occurrence in my truck is certainly problematic and bothersome under normal driving conditions. It is very bad and truly disappointing, especially considering the five previous Silverado's I purchased new and enjoyed didn't have this severe drivetrain problem. I'm not enjoying the 2012 4WD Silverado LTZ (a very high-end model) because of this problem.

The problem I'm left to infer is a performance feature from what the GM service departments explain. I infer this when told by GM Service Departments explaining that they find my truck performing similarly to other like-year models after driving mine.

OK, now this is not trivial! The metal-on-metal noise heard when as it occurs is bad. Eventually something is going to break when metal to metal slam together hard enough to hear inside the cabin. When whatever is slamming together gives-out, a catastrophic failure will occur. Who knows if this failure will result in an accident. Has it? It's my opinion that it will result is a stranding, since it occurs in the drivetrain. Come on GM/Chevrolet. I suspect the catastrophic failure(s) occur after the warranty expires.

I'm sure the smart engineers and well-qualified technicians can fix this. Help, please.