177mph

Thats fine. I assumed the TSB's came out in order but perhaps they dont. Back to the question. Where do I find the engine serial number?

This is the language in the latest TSB: • Looking upwards from under the vehicle towards the rear of the Left Hand cylinder head, inspect the digits indicated on the sticker above to determine the build date of the engine. The first two digits circled are the build year (‘24 in this example), and the next three digits are the build day (day 114 in this example). If the engine was built BEFORE 24183, proceed to step 2. • If the engine was built on or AFTER 24183 no further action is required. Submit labor operation 9107922.

I have a 2024 Sierra Denali with the 6.2 motor. The latest TSB says that certain serial number motors are affected and certain ones are not. They say the dealer needs to check the engines serial number to confirm when it was built. The TSB says that the engine serial number is on the back of the left side cylinder head -and can be seen from underneath. I just crawled under there and looked EVERYWHERE. No serial number. Where else can it be found?? (Keep in mind this is NOT the VIN)

Good review. I agree with you. I have the 2024 Denali with the 6.2. Only on my second tank of gas so too early to say too much. Like the motor, camera, tailgate, screens, etc....

here's the update. Truck is at stealer. I gave them all the information on the trucks condition and the GM documented fixes (They seem to hate being told how to fix). The vibration is consistent with other trucks and is related to the transmission. The fix listed on GM's diagnostics site is converter replacement and a fluid flush. They are refusing to do the converter replacement and only doing the fluid flush. I cannot get them to change their repair no matter what I do. I will hopefully get the truck back tomorrow and see how it goes. I am expecting the same issue to come back in 3 months. Time for another brand.

It would seem from my research on the boards that it could be the converter in the 8 speed transmission. Truck vibrates badly at times below 2k rpm at light throttle.

I have the 8 speed. Is that the same?

2015 GMC Sierra Denali 6.2 long bed. Factory 22's. No modifications. 39k miles. I have been experiencing a vibration in the steering column and seat at low rpm from 20-60 mph. Usually below 2k rpm when at low throttle application. Vibration comes every few seconds and lasts 2 seconds. Not from the v8-v4 switch. Only thing that helps is running in tow/haul mode or manually shifting. Truck has also been in for service a few times with loud metallic bangs for upshifts and downshifts. Dealer found nothing. No codes. Is anyone else experiencing similar issues? Thanks.