Justinv113

Side note: If you are concerned about damage from leaving the shocks on, you can simply leave the bump stop extension bolted on to the axle so the bump stop will limit the travel instead of the shock being the limiting factor.

The shocks are longer on the at4. I replaced mine when I removed the block, but only due to the fact that i had king shocks from my old truck that fit perfectly after removing the block. I don't see any way for the stock at4 shocks to hurt anything if left in place, but if the suspension is completely bottomed out, then they may blow out. If they do get damaged, buy new ones that are the correct length for a non at4 pickup. Don't have much to lose.

One of my friends has over 70k miles on his 19 tb with a 5.3. Just had to get a new cam and lifter installed when the lifter failed. I'm not sure if it's as bad as the afm, but I'm not convinced the dfm is much better. Range device might be cheap insurance.

You're absolutely right. I disconnected it last week and the handling is largely unchanged. Its a win win. Smoother ride without any real compromise. I have not towed anything without the bar, though.

You can order them from an offroad/automotive shop of your choice. 9/16" square ubolts. Width of springs are 2.5". I think i got 7" long bolts and had to cut off around 1" after torquing everything down. Paid something like $40 for the set.

I didn't replace the shackles. Just removed blocks and bump stop spacers and replaced shocks with shorter ones. I haven't looked at the shackles on this truck, but I did change them on my 2011 and it was not a fun task. I would avoid it, if possible. Removing the blocks, or going with shorter ones, is a better alternative since you also decrease the chance of getting axle wrap.

Same here. Fenders are different on the gmc vs chevy, maybe that is the difference?

Interesting. I would expect them to be the exact same. Is yours a shortbed, or standard?

They need 2" to 2-1/4" to be level. I yanked the block on the rear of mine and it measured 2". That brought it down to nearly level. May have still needed 1/4" after that to be perfectly level. If your going to try to bring the front up to match the rear, plan on getting upper control arms.

I forgot to mention that I have king 2.5" piggyback shocks in place of the ranchos on the rear. Just so happened that after removing the rear block on the AT4, the shocks are the same length from the previous generations, so I was able to cop them off of the old pickup. Those were a dramatic difference over the stocks. Definitely recommend getting bilsteins to replace the junky ranchos on the rear. King 2.5's are almost certainly not needed to tame the rear of these trucks. I can elaborate more if needed.

1/8" over the stock height of the AT4, so it would basically be 2" of lift for a non TB/AT4 pickup. Ride quality is not as impressive as I was expecting. Had high hopes. It does ride better, but definitely more firm. It is a pretty good improvement in the dirt and on larger bumps. Small bumps are a little better than the ranchos, but nothing stellar. What I consider "small bumps" would be your typical back road that gets neglected by the county and is always getting those cheap pothole repairs rather than getting repaved. On my 2011 silverado 1500, I had uca's and extended travel, custom valved, fox 2.5" remote reservoir coilovers from Accutune. The 6112 does not match that setup, but its also less than 1/3 the price. I have yet to disconnect the sway bar to see if that helps with the 6112 package. It helped with my previous setup, but the sway on turns was noticeable. Unsure as to wether the fancy traction control in the new truck will disagree with added body roll. I'll definitely try it out though.

Installed the 6112 a couple weeks ago on my AT4 with the 5.3. Coils settled to exactly 1/8" of lift on postion #5.

The 6112's come with new coils. You only reuse the top hat from the oem coilover. Uca's are probably not needed for most drivers, but they will improve the ride quality some at higher lift settings because they will allow for another 1-2" of droop. I have not found good dimensions on the 6112's, but they advertise pretty much the same allowable lift as the 5100's, so I'm assuming they are the same extended/compressed lengths. If that is the case, then they will have more travel than the factory shocks, so the uca's will be able to utilize the additional droop. If you get shocks that are the same extended length as the factory ones, then there is no need for uca's because the shock will be the limiting factor, when it comes to droop/extension. If you get 0-1" lift rear shocks, they will still bolt on and work, but they will limit the droop of the rear axle. Basically, if you add 2" of lift to the rear, the 0-1" shocks will be near their full extension at ride height. You can jack the back of the truck up and measure how many inches the rear suspension unloads before it stops, and that will show you how much down travel there is. The shock is the limiting factor, so if you add 2" blocks then you will lose 2" of that droop, but you load capacity will remain the same, and you will not need to add bumpstop extensions. Adding 2" of lift in the rear, you would ideally want longer shocks and possible a 1-2" bumpstop extension to prevent the longer shocks from bottoming out and getting damaged. If you never haul anything with the pickup, then you will not likely bottom out the rear, and you could probably get by without bumpstop extensions.

I pulled the rear lift blocks, shocks, and 2" bump stop spacers. Basically just removed the rear lift so it is the same as a non at4. I had 2.5" piggyback kings from my 2011 silverado and they bolted in perfectly. Make sure to get new u bolts. Also needed to adjust the headlights slightly- about 1/4 turn downward. End result was all fender heights are within 1/8" of each other.

If you want to know if you have afm or dfm, you can check the rpo codes. L84 is for dfm. To check the rpo codes on these t1 pickups, there is a QR code on a sticker that is on the door jam between the front and rear doors on the drivers side.

I've got a set of 6112 on order. Planning to set them at position #5. Hoping it will match the stock height on my AT4. I'll measure before and after and post results.

I would hold off on ordering air bags just yet. I have the mini packs on my mid traveled 2011 silverado. Towing capacity does not seem to be an issue at all. I have not pushed it anywhere near max capacity, but for any normal activity like throwing tools or motorcycles in the back, the springs barely squat. Ride is definitely improved though. I can easily pull a small trailer with a 1500 pound sxs along with my dirtbike and gear in the bed. Compresses maybe 2”. Nowhere near the bump stops.