GM released its first 2027 GMC Sierra 3500 HD equipment list on September 18, and I read all of it so you would not have to. The short version for a one-ton buyer: both engines wear new codes, all three transmissions now carry the Allison name, the 17-inch dually wheel is gone, single-rear-wheel GVWR moves up on every model, and adaptive cruise control is standard on all six trims. The trims, the cab and dually rules, the eight colors, and the Max Trailering Package all carry over.
The longer version includes the part most dealer websites skip. GM has not published horsepower, torque, towing, payload, or curb weight for 2027, so you will not find a 2027 rating anywhere on this page. If you need a fully rated one-ton this fall, the 2026 GMC Sierra 3500 HD buyers guide covers the trucks on our lot with every number already stamped in the door, and the buy-now-or-order-a-2027 post weighs the two against each other.
On This Page
- What GM has actually published for 2027
- Two new engine codes, and why we are not quoting horsepower
- The 17-inch dually wheel is gone
- Single-rear-wheel GVWR moves up to 12,700 pounds
- Adaptive cruise, bicyclist braking, and an SLT Technology Package
- What did not change
- How to spec a 2027 order using only what is verified
What Has GM Actually Published for the 2027 Sierra 3500 HD?
Equipment, not ratings. GM has published the trims, the cabs, the engine codes, the wheels, the packages, the safety content, the colors, and the GVWR menu. GM has not published horsepower, torque, conventional or gooseneck towing, payload, curb weight, GCWR, or dimensions. Both halves of that matter when you are deciding what to order and when.
| Item | 2026 Sierra 3500 HD | 2027 Sierra 3500 HD |
|---|---|---|
| Engine codes | L8T gas V8, L5P Duramax, output published | L8S gas V8 with direct injection and variable valve timing; L6P Duramax turbo-diesel V8, B20-compatible; output not published |
| Transmissions | 10-speed automatic | Allison 10-speed automatic on both engines, plus the power-take-off version on Pro and SLE diesels |
| Dually wheels and tires | 17-inch steel on Pro, SLE, SLT; 18-inch forged on Denali trims | 18-inch on every dually, steel or polished forged; LT235/80R18 the only dually tire |
| Single-rear-wheel GVWR ceiling | 12,250 lb | 12,700 lb, 4WD Crew Cab long bed Duramax |
| Dually GVWR | 14,000 lb | 14,000 lb, unchanged |
| Cruise control | Conventional on Pro, SLE, SLT; adaptive by package | Adaptive standard on all six trims |
| Technology Package | AT4, Denali, Denali Ultimate | Adds the SLT |
| Towing, payload, GCWR | Published by configuration | Not yet; to be published in the GM Trailering Guide |
Everything in that table is what GM printed, not what a forum guessed. Where GM is silent, this page is silent too. The 2027 Sierra 3500 HD buyers guide carries the trim-by-trim detail; the sections below explain what each change means with a loaded gooseneck behind you on a county section line.
Two New Engine Codes: Why Are We Not Quoting Horsepower?
Because GM has not printed it. For 2027 the gas engine is code L8S, described as a V8 with direct injection and variable valve timing, and the diesel is code L6P, described as a Duramax turbo-diesel V8, B20-compatible. Neither line carries a displacement, a horsepower figure, or a torque figure anywhere in the 2027 material.
For reference, the 2026 Sierra 3500 HD on our lot is rated by GM at 401 hp and 464 lb-ft on the gas V8 and 470 hp and 975 lb-ft on the Duramax, and those 2026 figures sit in the 2026 engine section where they belong. I am not moving them into the 2027 column and hoping.
Availability is verified, and one line of it changed. The gas V8 is standard on the Pro through the Denali with the 3.73 axle, and E85 capability is dropped. The Duramax is standard on the Denali Ultimate and available on every 4WD model and the 2WD Regular Cab; a 2027 2WD Crew Cab or Double Cab is gas only. Around here that is a footnote, because a one-ton headed for a gooseneck and a snow blade is a 4WD truck anyway.
Every 2027 Duramax still includes the block heater, the exhaust brake, the 220-amp alternator, and the 730 CCA battery, the winter grille cover is still diesel-only, and filter regeneration is now included on all six trims instead of being a fleet item. The other change is the name on the gearbox: the gas, diesel, and power-take-off transmissions are each printed as an Allison 10-speed automatic, and the power-take-off version is still limited to the Pro and SLE. The 2027 engine section keeps the current wording as GM updates it.
What a new engine code does and does not mean
A new code says GM revised or replaced something, not what. Any site printing a 2027 horsepower number or a 2027 tow rating today is guessing or copying the 2026 figure, and at the one-ton level that is not a harmless shortcut. When the 2027 GM Trailering Guide lands we will update this post the same day.
The 17-Inch Dually Wheel Is Gone: What Rides Under a 2027 Dually?
Every 2027 Sierra 3500 HD dually rides on 18-inch wheels and LT235/80R18 tires from the factory. The Pro gets an 18-inch silver painted steel wheel; the SLE, SLT, Denali, and Denali Ultimate get the 18-inch polished forged aluminum wheel, with Denali center caps on the two Denali trims. The 17-inch steel dually wheel, its caps, its chrome skins, and the 17-inch tire are all out for 2027.
For an outfit that runs duallys, this is a parts-room change more than a styling change. You carry one tire size across all six corners and the spare, and it is the same all-terrain the 2026 Denali dually and the Max Trailering truck already wore, so it is a known quantity at every shop between here and Aberdeen. The full write-up on the 2027 dually wheel and tire change covers what it means at replacement time.
The single-rear-wheel ladder is untouched, from 18-inch steel and machined aluminum up through the 20s, which remain single-rear-wheel only; there is still no 22-inch wheel on a one-ton. Full detail sits in the 2027 wheels and tires section.
The 18-inch polished forged dually wheel used to be a Denali and Max Trailering item. For 2027 it is what an SLE or SLT dually comes on, and every dually shares one tire size.
Single-Rear-Wheel GVWR Moves Up: What Does 12,700 Pounds Tell You?
It tells you a 2027 single-rear-wheel truck is allowed to weigh more, loaded, than its 2026 counterpart was. GVWR is the most the truck may weigh with people, fuel, cargo, and the pin or tongue weight of the trailer on it. Every 2027 single-rear-wheel configuration moves up 250 to 450 pounds and the ceiling lands at 12,700 pounds. The dually did not move: still 14,000 pounds, still tied to a long bed.
| Configuration (SRW = single rear wheel) | 2026 GVWR | 2027 GVWR |
|---|---|---|
| 2WD Regular Cab long bed, gas, SRW | 10,950 lb | 11,250 lb |
| 4WD Crew Cab standard bed, Duramax, SRW | 12,100 lb | 12,500 lb |
| 4WD Double Cab long bed, Duramax, SRW | 12,150 lb | 12,500 lb |
| 4WD Crew Cab long bed, Duramax, SRW | 12,250 lb | 12,700 lb |
| Any dually, long bed | 14,000 lb | 14,000 lb |
Here is the part to be careful with. GVWR is not the trailer rating, and it is not GCWR, the total for truck and trailer together. A higher GVWR usually means more payload, but payload is GVWR minus what the truck weighs empty, and 2027 curb weights are unpublished, so there is no honest 2027 payload number to hand you. What I can tell you is what the rated truck does: the 2026 4WD Crew Cab long bed dually with the Duramax carries up to 5,647 pounds and pulls up to 31,000 pounds with a gooseneck, properly equipped, and those 2026 figures live in the 2026 towing section.
On any Sierra HD the last word belongs to the trailering information label in the driver door jamb of that truck, because cab, bed, drive, engine, and packages all move the number. Until the 2027 ratings land, the 2027 GVWR section is the only capability figure we publish for the new truck.
Adaptive Cruise, Bicyclist Braking, and an SLT Technology Package: What Is New Inside?
Three changes, and the first matters most to the buyers who never get the options. Adaptive cruise control is standard on all six 2027 trims, Pro included, and conventional cruise is no longer listed; for 2026 the Pro, SLE, and SLT had conventional cruise and adaptive took a package. A Pro work truck now holds its following distance on Highway 12 the same way a Denali Ultimate does, which on a February morning with a loaded stock trailer behind you and a grain truck ahead is worth more than any chrome.
Second, the standard Sierra HD Pro Safety group renames one piece: Front Pedestrian Braking becomes Front Pedestrian and Bicyclist Braking. The rest of that group is unchanged and standard on every trim, and Pro Safety Plus still adds Trailer Side Blind Zone Alert, Rear Cross Traffic Alert, park assist, and the bed view and surround vision cameras on Crew and Double Cabs.
Third, the Technology Package, the rear camera mirror plus the 15-inch head-up display, reaches the SLT for the first time with the SLT Preferred, SLT Premium, or Texas SLT Premium Package; for 2026 it was AT4 and up only. The SLT dually is the volume one-ton on our lot, and that camera mirror is the piece I push hardest for anyone pulling a tall gooseneck, because a loaded trailer blanks a mirror and the camera sees past it. Power-retractable assist steps are now available on the Denali as well as the AT4.
What Did Not Change for 2027?
Most of the truck, and every rule that decides how you order one. The six trims are the same, with no AT4X at the one-ton. The Pro comes as a Regular, Double, or Crew Cab in 2WD or 4WD; the SLE in all three cabs, 4WD only; the SLT, AT4, Denali, and Denali Ultimate as Crew Cab 4WD only. The AT4 is still single rear wheel only, a dually still requires a long bed and the 14,000-pound GVWR, and the Denali Ultimate is still diesel only.
The Max Trailering Package carries over with the same content and the same narrow rules: a Pro, 2WD, Regular Cab, dually, Duramax option bringing heavy-duty front springs, the polished forged 18s, the dually all-terrain tire, and gooseneck prep, still without a spray-on bedliner or bed rail caps. Gooseneck prep stays on all six trims, the ball kit is still there, and Snow Plow Prep and Camper is still offered on all six trims including duallys as long as the truck is 4WD. Camper springs, the off-road package on single-rear-wheel trucks only, power take-off on the Pro and SLE, dual alternators, the vehicle module, upfitter switches, high idle, and the bed delete all carry over.
Trailering hardware is unchanged, which is the sentence a hauler cares about: the hitch with 7-pin and 4-pin connectors, hitch guidance, the integrated brake controller, and the trailering information label are standard on every trim, ProGrade Trailering is standard from the SLT up, trailer tire pressure sensors are offered, and power trailering mirrors are still required on a dually. Inside, the screens, the Bose systems, the MultiPro tailgate ladder, and the interior menu carry over, and all eight exterior colors return with nothing added and nothing dropped.
How to Spec a 2027 Sierra 3500 HD Order Using Only What Is Verified
You can build a sound 2027 one-ton order today without a single unpublished number, because every decision that matters is an equipment decision.
- Start with single rear wheel or dually: weigh the pin of your heaviest trailer, not the trailer total. If the pin pushed you out of a three-quarter-ton, you are ordering a dually, which means a long bed and the 14,000-pound GVWR.
- Pick the engine by the job: the Duramax if you pull a gooseneck weekly, want the power-take-off transmission, or want the exhaust brake coming off the river breaks. Order it on a 4WD model or a 2WD Regular Cab.
- Choose the cab and bed next: this sets your GVWR and, on a single-rear-wheel truck, decides whether you land at 12,500 or 12,700 pounds.
- Decide gooseneck prep and Max Trailering now: neither bolts on later the same way. Gooseneck prep fits any trim; Max Trailering is only that 2WD Regular Cab dually with the Duramax.
- Layer the winter and upfit equipment: plow prep and dual alternators for a blade and beacons, the vehicle module and upfitter switches for a bale bed or hotshot deck, high idle for job-site work.
- Read the label the day it lands: the trailering information label in the driver door jamb carries that truck's payload and trailer ratings. Scale your loaded rig and compare before you hook to anything.
Is the 2027 Sierra 3500 HD the One to Order?
| Worth it if | Skip it (buy the rated 2026 on the lot) if |
|---|---|
| You run duallys and want one 18-inch tire size You want adaptive cruise on a Pro or SLE without buying a package You are an SLT buyer who wants the camera mirror and head-up display You carry heavy single rear wheel and want the higher GVWR ceiling Your truck can build over the winter in the exact spec you want |
You need a published gooseneck rating and payload before you sign Calving, a hay contract, or a snow contract needs the truck this fall You want to see, drive, and scale the exact truck first You are matching the truck to a trailer already close to the limit You wanted a 2WD Crew Cab dually with the Duramax |
Key Takeaways
- New engine codes, L8S gas and L6P Duramax, and all three transmissions are now printed as Allison 10-speeds.
- GM has not published 2027 horsepower, torque, towing, payload, or curb weight; those come in the GM Trailering Guide.
- Every 2027 dually rides on 18-inch wheels and LT235/80R18 tires; the 17-inch dually wheel is gone.
- Single-rear-wheel GVWR rises 250 to 450 pounds to a 12,700-pound ceiling; the dually stays at 14,000.
- Adaptive cruise is standard on all six trims and the Technology Package reaches the SLT; trims, cab rules, colors, and Max Trailering rules are unchanged.
Frequently Asked Questions
Is the 2027 GMC Sierra 3500 HD engine new?
The codes are new. For 2027 the gas engine is L8S, a V8 with direct injection and variable valve timing, and the diesel is L6P, a Duramax turbo-diesel V8 that is B20-compatible. GM has not printed displacement, horsepower, or torque for either one. Both pair with an Allison 10-speed automatic.
What is the 2027 Sierra 3500 HD towing capacity?
Not published yet; 2027 output and trailer ratings will be published in the GM Trailering Guide. The rated 2026 Sierra 3500 HD on our lot pulls up to 20,000 pounds conventional on a Duramax, and a 2026 4WD Crew Cab long bed dually is rated up to 31,000 pounds with a gooseneck, properly equipped. When a 2027 arrives, the trailering information label in its door jamb carries that truck's rating.
Are 17-inch dually wheels still offered on the 2027 Sierra 3500 HD?
No. Every 2027 dually comes on 18-inch wheels and LT235/80R18 tires: silver painted steel on the Pro and polished forged aluminum on the SLE, SLT, Denali, and Denali Ultimate, with an 18-inch spare. The 17-inch steel dually wheel, its chrome skins, and the 17-inch tire are no longer listed.
Can I order a 2027 Sierra 3500 HD Crew Cab with two-wheel drive and the Duramax?
Not as GM has it listed today. For 2027 the Duramax appears on every 4WD model and on the 2WD Regular Cab; the 2WD Crew Cab and Double Cab are gas only. If you want the diesel in a crew cab, order a 4WD truck, or call or text 605-845-7277 and we will check the current order bank first.
My Take on What Is New for 2027
The honest headline is that the 2027 Sierra 3500 HD is a better-equipped version of a truck that did not need fixing, with one large unknown hanging off the back of it. Eighteen-inch wheels on every dually, a higher single-rear-wheel GVWR, standard adaptive cruise on a Pro, and the camera mirror finally reaching the SLT are all real and all verified. The engine codes changed and the ratings are not out, and I would rather say that plainly than print a gooseneck figure I cannot defend at the scale house.
If your outfit can wait for a truck that builds over the winter, spec it on equipment the way the steps above lay it out, and ask us where the order bank sits. If you need a rated one-ton before calving, the 2026 trucks in the yard are the same six trims with every number already in the door.
The full trim, wheel, GVWR, package, and safety detail lives in the 2027 GMC Sierra 3500 HD buyers guide, and the rated truck sits in the 2026 buyers guide. Or stop by Beadle Chevrolet GMC at 2200 US Hwy 12 in Mobridge, weekdays 8:00 a.m. to 5:30 p.m. and Saturday until noon, or call or text 605-845-7277, and we will build the order sheet together.
About the Author
Lexy Tabbert — Beadle Chevrolet, Mobridge, SD
Lexy Tabbert is the Director of Sales and Marketing at Beadle Chevrolet in Mobridge, South Dakota. She covers Chevrolet and GMC vehicles, trim comparisons, and buyer guidance — helping families, ranchers, and ag operators across the region find the right truck and configuration for their needs. Learn more about Lexy.