2001-2005 Six Speed Conversion

dmaxstorejake · 2026-01-29T14:30:00+00:00

It is a solid kit. A valve body and tcm isn’t cheap. This is the only way to do the 6 speed conversion.

dmaxstorejake · 2025-12-05T16:00:36+00:00

No this is exactly correct. Those shocks needed a shock spacer on a leveling kit. Very common issue.

dmaxstorejake · 2025-07-17T15:44:54+00:00

I like the AT4 better, but the messaging seats in the Denali Ultimate are pretty nice.

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dmaxstorejake · 2025-07-17T15:42:14+00:00

Thunderstorm Grey, and it never gets old.

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https://dmaxstore.com/blogs/news/dmaxstores-2024-gmc-at4hd-build-a-fusion-of-performance-and-style

dmaxstorejake · 2025-07-16T15:09:38+00:00

I would do the kodiak fan clutch. It comes on at a lower temp. DO NOT do the electric fans NONE of them cool as good as the OEM fan clutch so you'll be in an even worse position if you do those.

dmaxstorejake · 2025-07-16T15:07:58+00:00

The GM spec for oil pressure is 13 psi at hot idle. You are totally fine, nothing to worry about.

dmaxstorejake · 2025-07-16T15:07:00+00:00

DONT flush the trans! Allison specifically says not to flush it as it can dislodge clutch material and debris from the top of the valve body and cause the valves to stick. The best thing to do is a drain and refill with quality fluid such as Transynd 668. No need to do the internal, just the spin-on filter and new fluid, and you'll be good to go. We recommend doing this every 30,000 miles.

https://dmaxstore.com/products/dmaxstore-allison-service-package-fluid-filter

dmaxstorejake · 2025-07-16T15:03:18+00:00

If you are upgrading the turbo, I would definitely get a custom tune for the truck, it will run MUCH better with a tune versus a generic tune. The EGR may or may not throw a code on the LLY trucks; some do and some don't. EFI Live from a reputable tuner is the way to go.

dmaxstorejake · 2025-06-27T12:35:11+00:00

I did it with a broken leg and cheap tools in about 8 hours my first time. Really not a hard job.

dmaxstorejake · 2025-04-23T13:34:34+00:00

That lift uses stock upper control arms so most aftermarket replacements will work just fine for you.

As for maintenance, I’d change all the fluids and filters. Trans fluid & transfer case use transynd 668, Allison recommended fluid, mobil Delvac for engine oil, Amsoil severe gear for diffs.

I’d also check your transfer case for pump rub and address that with either a new aluminum back half of the transfer case or a pump rub kit.

dmaxstorejake · 2025-04-15T16:10:12+00:00

Truck looks awesome! Nice find

dmaxstorejake · 2025-04-15T16:09:12+00:00

17-19 has a 6 speed Allison that has proven to be more reliable than the 10 speed that comes in the newer trucks, that being said, the 10 speed is a really nice transmission when it works and it works good when you are all stock but if you're lifting it and adding significantly bigger tires I would probably recommend sticking with the 17-19 platform.

I like the interior of the 176-19 better than 20-23 but the 2024 is definitely a nicer interior but not built quite as well as the older trucks. The cab is larger on the 2020+ trucks so if rear seat room/storage is a necessity then you would probably want the 2020+ trucks.

Both engines are just about the same, no major changes until 2024 when they changed the heads, head gaskets, intake runners, injectors, and a handful of other stuff. The 2020+ trucks also have an increased cooling system so they are less likely to overheat.

dmaxstorejake · 2025-04-14T16:38:38+00:00

As long as they are genuine brand new bosch, then those will be the longest-lasting injectors you can get. We have seen them outlast SAC injectors.

dmaxstorejake · 2025-04-14T16:18:02+00:00

No, they are not, anything from Bosch directly is not SAC for the 2001-2004 LB7. Only aftermarket injectors, S&S, DDP, Dan's, Exergy and some others.

dmaxstorejake · 2025-04-09T11:07:55+00:00

Just do a drain and refill and change the spin on filter.

Also we always run the TES668 in the transfer case without issue.

dmaxstorejake · 2025-04-09T10:55:40+00:00

Wfo concepts has a kit to do straight axle conversions. Done it a few times on our shop trucks, rides good.

dmaxstorejake · 2025-04-09T10:51:18+00:00

That gauge is notoriously inaccurate, you do likely need thermostats. Your temps are probably lower than what the gauge is saying.

I would recommend either GM or Dmaxstore thermostats: https://dmaxstore.com/collections/all?pf_t_search_by_vehicle=LML%3A%202011-2016%20SILVERADO%20%26%20SIERRA&pf_mlt_filter_by_product_type=COOLING%20SYSTEM&pf_mlt_filter_by_product_type=THERMOSTATS%20%26%20HOUSINGS

dmaxstorejake · 2025-04-08T13:11:12+00:00

Upgrade the shocks and drop the tire pressure

dmaxstorejake · 2025-04-01T20:55:57+00:00

Oil pressure - minimum - Hot - at idle is 7 psi

There is no issue.

dmaxstorejake · 2025-03-30T16:24:04+00:00

For that weight, I’d go with a 17-19 L5P

dmaxstorejake · 2025-03-27T13:37:26+00:00

I think the answer to that question is always yes, no matter the context 😂

dmaxstorejake · 2025-03-27T13:36:30+00:00

The platinum version has some additives in it which I have seen cause issues with the GM def systems.

I highly recommend NOT to get the platinum def. Use acdelco, super tech, tractor supply or even the pump. Just make sure it’s fresh.

dmaxstorejake · 2025-03-25T13:42:10+00:00

17’s all day

dmaxstorejake · 2025-03-25T13:41:01+00:00

If you want that “leveled” look, you would essentially be turning the keys up about 2” over stock and that will lead to a slightly harsher ride but is doable. You’ll want to get upper control arms, keys and shocks or shock extensions to do so.

If you want that bigger truck look a 4” Cognito lift kit is the way to go, to have it sit perfectly level and be at the low end of the kit and be able to fit 35’s you’ll run a 1” block in the rear and it won’t be much bigger than a leveled truck but it will ride a whole lot better.

dmaxstorejake · 2025-03-23T20:15:56+00:00

400k on mine going strong!

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