Kenster113

X2 on if the compatibility brackets are required, without the manual I can’t tell what they are for.

Looking into this too, mostly curious about adding task lighting to my LT. Kinda regret not looking into before I added my fog lights so I could have at least ordered the kit with the task lighting switch instead.

I’ve got a ‘21 LT 1500 with same exact issues, and it has the SU4 Code. Noticed the ticking more or less around 1500 miles. But it would come and go. Now at 8k miles, there’s no missing it. I thought the jingle/tick was normal noise being the engine itself is already loud but that jingle and tick has turned into binding, clunking and thumping, all from the front diff. I thought it might have been the axles, but they are actually ok. I found play on the inner driver side. You guessed it, at the seal area. It moves so much it’s like there is another joint behind the seal. My guess is that whatever that issue may be is causing my clunking upon bumps and turning, and it’s weird that it only does it if I turn hard before ‘warming up’ (Ex. Backing out of driveway in the morning) OR it happens consistently at every turn after ‘warm up’, so often it makes driving through lots and parking embarrassing. I have the trailboss lift, and ready lift level. Explained to ready lift the issue and they state their lift is completely compliant even with the TB lift added and should any issue arise with me and my warranty because said level that I can have the dealer contact them directly. And since it is a published bulletin, it acknowledges that GM is aware that the SU4 code has been an issue for some trucks regardless. contacted my dealer’s service department before bringing in my truck, the advisor is speaking with his warranty consultant now as he hasn’t heard of any trucks come back to them with issues concerning the front differential (SU4). Hopefully this issue goes smooth. Love the truck but hate this issue. Just want it working right.

Pulled CVs and swapped out for Trailboss axles. Turns out the standard ones are actually ok. Looks like the clunk I get is from the diff itself. I can pull on the Inner CV cup and the dust seal on the diff comes with it, the axle itself as no lateral movement, about 1/4” movement between dust seal and the diff itself. Almost like the bearing behind the seal isn’t pressed in all the way? I have a video but it exceeds file limit.

I want to know where this leads. I’m sure there’s a solution, seems like there’s a lot you can do with these new truck to upgrade things here and there down the line. Maybe get into contact with White Automotive, they specialize in programming and the electronics of these truck so they might have some clues.

Have the Trailboss lift on mine, did not use the trailboss axles as the lifted shocks were ‘donated’ to me. But I knew what I was getting into as I saw people were running 3in up front on non-trailboss models and turning out ok.. Worked well for about 3-4K miles but unfortunately I now have a clunk when turning and going over certain bumps, might be from the CVs. The new UCAs did absolutely help the ball joint angles, I don’t have pictures for comparison but I will say that I wasn’t satisfied with the angle of the stock UCAs with that much lift. Now i just need to locate some Trailboss axles and wheel spacers as the RL UCAs are so beefy they nearly touch.

I’m having the same exact issues as most of you were having or had. I’ve got a ‘21 5.3 8spd CC Silverado. I can’t recall if mine has the shim but it would be worth trying. Had the truck at the dealer and they couldn’t find much, said they didn’t feel what I was feeling but I’m not sure why as I feel it nearly all the time, only time I don’t completely feel the rumble is if coming to a stop at slow moving speeds. The shop foreman noted I had a muffler delete and said that could be causing a back pressure issue and it could be what’s affecting the engine and transmission. Plausible, but I did notice it when it had the muffler on. im hoping it be the shim issue, as one other said, it does feel like a humming vibration is present when driving against a fair wind.