1500 AT4 3.0L Duramax; Level with Bilstein and UCA's

AdrianAT4 · Jan 31, 2024

Hey guys, I feel this question has been answered a million times, but this mainly pertains to the 3.0L engine.

I'm trying to level my truck by adjusting the front only and putting on 35" Nitto Trails. I've read a lot about Bilstein shocks, but Bilstein only recommends the B8 5100 shocks. I also read about Cognito SM series UCA's, which I will acquire.

My question is if the Bilstein shocks on OEM coils will be good enough to level the truck, be good to support the 3.0L added weight, and clear 35" tires. I'm okay with trimming, not a problem. I just don't want any issues before ordering parts.

If not, I'm curious to explore alternatives that y'all recommend. Lmk and thank you in advance.

TonyAT4 · Feb 1, 2024

What rims and offset are you running? 35’s will probably need a decent amount of trimming. The 5100’s will give you 1.2” at the highest setting I believe, truck will still have a slight rake.
They don’t recommend stacking spacers on top of the 5100’s due to geometry and travel of the shocks but I’m sure someone has done it.
You could get the Readylift 1.75 kit with the UCA’s or the SST kilt for a 2” front lift and 1” rear lift (3” blocks). I’m sure others will check in with suggestions or just do a search on this site.
Good luck.

TonyAT4 · Feb 1, 2024

The 6.2 and 3.0 are very close in weight around 465lbs, the 5.3 is around 430lbs.

AdrianAT4 · Feb 1, 2024

TonyAT4 said:
What rims and offset are you running? 35’s will probably need a decent amount of trimming. The 5100’s will give you 1.2” at the highest setting I believe, truck will still have a slight rake.
They don’t recommend stacking spacers on top of the 5100’s due to geometry and travel of the shocks but I’m sure someone has done it.
You could get the Readylift 1.75 kit with the UCA’s or the SST kilt for a 2” front lift and 1” rear lift (3” blocks). I’m sure others will check in with suggestions or just do a search on this site.
Good luck.

I will do it on stock rims to get the bubba look.

RockCrawlin · Nov 27, 2024

TonyAT4 said:
What rims and offset are you running? 35’s will probably need a decent amount of trimming. The 5100’s will give you 1.2” at the highest setting I believe, truck will still have a slight rake.
They don’t recommend stacking spacers on top of the 5100’s due to geometry and travel of the shocks but I’m sure someone has done it.
You could get the Readylift 1.75 kit with the UCA’s or the SST kilt for a 2” front lift and 1” rear lift (3” blocks). I’m sure others will check in with suggestions or just do a search on this site.
Good luck.

My understanding of the recommendation is to not put spacers on top of the 5100s if the ring is set higher than stock. The reason is the added height to the AT4 would change the geometry to exceed max spec for the lower control arm and the diff. If you exceed 2" higher than stock, not only is the recommendation to get UCAs, but also to drop the diff to maintain axle angles.

SmittysAT4 · Oct 27, 2025

RockCrawlin said:
My understanding of the recommendation is to not put spacers on top of the 5100s if the ring is set higher than stock. The reason is the added height to the AT4 would change the geometry to exceed max spec for the lower control arm and the diff. If you exceed 2" higher than stock, not only is the recommendation to get UCAs, but also to drop the diff to maintain axle angles.

Old thread but a topic that has been coming up. This sounds exactly correct from what I have learned here on the forum. My understanding is going from a stock AT4 we should not go more than 2" higher as that puts the suspensions geometry right at the point where a diff drop would be required for CV angles and such. I have seen a few on here that have done either the Bilstein 6112s or 5100s or Fox 2.0s and added the max 1" to 1.2" that they offer then add a piece of another level kit to the mix. From what I see the best option would be to add the lower "C" shock spacer to one of those for a little added lift. As long as the total netted lift is at or under 2" we should be good? If anyone here could please chime in on this that would be great! I am currently considering adding the lower "C" shock spacer to my Cognito 1" kit in an effort to get to around 1.5" to 1.75" lift. Any input, been there done that advise would be great! Thx!!