2027 Silverado HD: 8.3L Duramax Diesel vs. 6.6L Gas V8. Which One Should You Buy?
2027 Silverado HD · Duramax vs. Gas · Okarche, OK2027 Silverado HD: 8.3L Duramax diesel vs. 6.6L gas V8. Which one should you buy?
Quick answer The 8.3L Duramax is an $11,400 option that buys 555 hp and 1,230 lb-ft against the standard 6.6L gas V8’s 412 hp and 472 lb-ft, a factory exhaust brake, and tow ratings that run from 2,500 lb higher on a ball hitch to roughly double on a gooseneck once you add the Max Trailering Package. The gas V8 carries 820 lb more payload (6,990 vs. 6,170 lb), costs less to buy and maintain, never needs DEF, and is the only engine offered on 2WD crew cabs. Rule of thumb: if the truck’s job is a heavy trailer every week, buy the diesel; if its job is weight in the bed or a body, buy the gas. Carter is taking 2027 orders now and prices both on the same truck so you can see the payment difference.
Side by side
| 6.6L gas V8 (L8S) | 8.3L Duramax turbo-diesel V8 (L6P) | |
|---|---|---|
| Output | 412 hp / 472 lb-ft | 555 hp / 1,230 lb-ft |
| Transmission | Allison 10-speed automatic (MKM) | Allison 10-speed automatic (MGM); MGU with integrated PTO |
| Axle ratio | 3.73 | 3.42 |
| Price | Standard | +$11,400 on any trim |
| Fuel | Regular unleaded | Diesel + DEF; B20 biodiesel compatible |
| Included with engine | – | Exhaust brake (K40), diesel particulate filter with manual regeneration (FPF), engine block heater (K05) |
| Options that require it | – | Max Trailering Package (NHT), Power Take-Off (PTO, WT/Custom/LT) |
| Max towing, 2500HD | 19,000 lb gooseneck (Regular Cab 2WD) | 23,200 lb gooseneck (Regular Cab 2WD, NHT) |
| 2500HD Crew Cab long bed 4WD, ball / gooseneck | 16,000 / 18,200 lb | 18,500 / 19,600 lb; 20,000 / 22,300 lb with NHT |
| 3500HD Crew Cab long bed 4WD dually, ball / gooseneck | 17,600 / 17,800 lb | 20,000 / 31,800 lb |
| Max towing, 3500HD | 18,500 lb | 38,000 lb (Regular Cab 2WD dually, NHT) |
| Max GCWR, 2500HD / 3500HD | 26,000 / 26,000 lb | 31,000 / 46,500 lb |
| Max payload (GM published) | 6,990 lb | 6,170 lb |
| 2WD availability | Every cab | Regular Cab only; 2WD Double and Crew Cab are gas-only |
| Replaces | 2026 6.6L L8T, 401 hp / 464 lb-ft | 2026 6.6L L5P Duramax, 470 hp / 975 lb-ft |
Tow ratings from the October 9, 2026 order guides for standard-equipped trucks with driver; the full towing chart lists every cab and axle. Output and payload are GM’s published figures. HD pickups over 8,500 lb GVWR are not EPA fuel-economy rated, so GM publishes no mpg for either engine.
What $11,400 actually buys
Strip away the badge and the diesel delivers five concrete things.
1. Torque where the trailer feels it
1,230 lb-ft against 472 is not a 20 percent difference, it is 2.6 times the twist. On a loaded gooseneck leaving a stop sign or climbing out of the Canadian River bottom on I-40, that is the difference between the transmission hunting and the truck simply going.
2. An exhaust brake
Standard with the Duramax, not available on the gas truck. Coming down a grade with 15,000 lb behind you, it holds speed without cooking the service brakes. If you run the Arbuckles or anywhere west of Oklahoma with a trailer, this alone is worth a lot.
3. Higher ratings, and access to the big ones
On a crew cab 4WD 2500HD, 2,500 lb more on the ball and 1,400 lb more on a gooseneck as-is. The Max Trailering Package, which takes the same truck to 22,300 lb gooseneck, and the 3500HD’s 30,000-plus dually ratings are diesel-only. GCWR goes from 26,000 to 31,000 lb on the 2500HD.
4. Options you cannot get otherwise
Power Take-Off for a hydraulic body, the integrated-PTO Allison (MGU), and the Max Trailering Package all require the L6P. If a bale bed with a hydraulic arm is going on the truck, that matters.
5. Resale
Diesel HDs have historically held value better than gas trucks in Oklahoma, where the next buyer is usually also pulling something. That is not a guarantee, but it is why the $11,400 does not vanish the way most options do.
What the gas V8 does better
- Payload. 6,990 lb vs. 6,170 lb maximum. The diesel engine, its cooling and its emissions hardware weigh several hundred pounds, and every one of them comes out of what the bed can carry. For a service body that weighs 1,000 lb before a tool goes in it, or a flatbed that hauls pallets rather than pulls, the gas truck is the right one.
- Price and payment. $11,400 is roughly $160 a month over 72 months before interest. On a WT that is the difference between a $47,200 and a $58,600 truck.
- Simpler upkeep. No DEF tank to fill, no diesel particulate filter to regenerate, no diesel fuel filters, regular unleaded at any pump. The DPF on the diesel will not allow a manual regeneration until it reads 100 percent full, which means a diesel that only ever makes 10-minute trips will spend time in regen cycles it cannot finish.
- 2WD crew cabs. If you want a 2WD Double Cab or Crew Cab HD, it is a gas truck; GM does not offer the diesel there.
- It still tows. 16,000 lb on the ball and 18,000-plus on a gooseneck in a crew cab, with 412 hp and the most standard torque in the class. A two-horse, a car hauler, a 20-foot equipment trailer or a 12,000 lb stock trailer is well inside that.
Which engine for which job
| The truck’s job | Our pick | Why |
|---|---|---|
| Ranch truck pulling a 20 to 24-foot stock trailer every week | 8.3L Duramax, 2500HD or 3500HD SRW | 12,000 to 16,000 lb loaded, long days, grades; torque and the exhaust brake earn their keep. Add Z6A gooseneck prep from the factory. |
| Service body or flatbed that lives on job sites | 6.6L gas | Body weight plus tools is a payload problem, not a towing problem; the gas truck carries 820 lb more and costs $11,400 less. |
| Bale bed with a hydraulic arm, occasionally pulling a trailer | Either; Duramax if you want PTO | Electric-over-hydraulic beds run on either engine; a PTO-driven system needs the diesel and the MGU transmission. |
| Fifth-wheel camper, 35 to 42 feet | 8.3L Duramax, 3500HD | 15,000 to 18,000 lb with 3,000-plus lb of pin weight; the dually’s 31,800 lb rating and 14,000 lb GVWR give you margin on both. |
| Hot shot or equipment hauling for hire | 8.3L Duramax, 3500HD dually | You are selling capacity; 31,800 to 38,000 lb gooseneck ratings and 41,000 to 46,500 lb GCWR are the product. |
| Plow, municipal or fleet truck, short trips | 6.6L gas | Short cycles are hard on a DPF; the gas truck idles, plows and runs errands without an emissions system to manage. |
| Family truck that tows a boat or a two-horse on weekends | 6.6L gas | Under 10,000 lb, a few times a month. Spend the $11,400 on the trim level or keep it. |
The 2026 option on the lot
The 2027 8.3L is a big step, but the outgoing 6.6L Duramax is still a 470 hp, 975 lb-ft engine, and the 2026 HDs on our lot are priced under MSRP with GM’s November cash on top: $1,000 customer cash on every 2026 Duramax plus $4,500 Red Tag bonus cash on Duramax LT and High Country ($3,000 on LTZ), through November 30. If your heaviest trailer is under about 18,000 lb and you need the truck this fall, a 2026 Duramax is the better deal today. If the 8.3L’s torque or the higher 2027 ratings are why you are buying, order the 2027; the order bank is open. Either way we will put both trucks on one sheet.
Frequently asked questions
How much more does the 8.3L Duramax cost on a 2027 Silverado HD?
$11,400 on any trim, per GM’s October 2026 pricing. A 2027 2500HD WT starts at $47,200 before destination with the gas V8 and $58,600 with the Duramax; a High Country is $75,400 gas and $86,800 diesel. 3500HD pricing had not been published as of this writing.
What does the 8.3L Duramax add over the 6.6L gas V8?
143 hp and 758 lb-ft of torque (555/1,230 vs. 412/472), a factory exhaust brake, a diesel particulate filter, an engine block heater, eligibility for the Max Trailering Package and the Power Take-Off option, and higher tow ratings: on a 2500HD crew cab 4WD, 18,500 lb on the ball vs. 16,000 and 19,600 lb gooseneck vs. 18,200, or 22,300 lb gooseneck with Max Trailering. Maximum GCWR rises from 26,000 to 31,000 lb on the 2500HD and from 26,000 to 46,500 lb on the 3500HD.
Does the gas 6.6L V8 have more payload than the Duramax?
Yes. GM’s maximums are 6,990 lb for the gas truck and 6,170 lb for the diesel, because the diesel engine weighs several hundred pounds more and that weight comes straight out of payload at the same GVWR. If your truck carries a service body, a flatbed load or a slide-in camper rather than pulling a heavy trailer, the gas V8 is usually the better tool.
Is the 2027 6.6L gas V8 different from the 2026 engine?
Modestly. The 2027 L8S is rated 412 hp and 472 lb-ft, up from 401 and 464 on the 2026 L8T, and it is paired with a 10-speed automatic that now carries the Allison name on the gas truck too. It remains naturally aspirated and runs on regular unleaded. It is still the engine with the most standard torque in the class, per GM.
Is the 8.3L Duramax a new engine?
Yes, all new for 2027. It replaces the 6.6L L5P Duramax (470 hp, 975 lb-ft) that GM has used since 2017. GM lists it as RPO L6P, B20 biodiesel compatible, paired with the Allison 10-speed automatic (MGM, or MGU with the integrated PTO).
Can I get a 2WD Silverado HD with the Duramax?
Only as a Regular Cab. GM’s 2027 trailering tables show the 8.3L on 2WD Regular Cab 2500HD and 3500HD trucks and on every 4WD cab, but 2WD Double Cab and Crew Cab trucks are gas-only. A diesel crew cab is a 4WD truck.
Should I buy a 2026 Duramax instead of waiting for the 2027?
If you need the truck this fall or the 6.6L Duramax’s 975 lb-ft already covers your trailer, the 2026 HDs on our lot are discounted under MSRP and GM has $1,000 customer cash on every 2026 Duramax through November 30, plus $4,500 Red Tag bonus cash on Duramax LT and High Country ($3,000 on LTZ). If the 8.3L’s 1,230 lb-ft or the higher 2027 ratings are the reason you are buying, order the 2027; Carter is taking orders now. The HD specials page has the current program and in-stock trucks.
Related
All three Duramax engines: 3.0L, 6.6L and 8.3L compared · 2027 Silverado 2500HD and 3500HD: pricing, engines, release date · 2500HD vs. 3500HD · Gooseneck and fifth-wheel towing · 2027 Silverado HD towing capacity, every configuration · 2027 vs. 2026 Silverado HD: what changed · Silverado HD specials · The 3.0L Duramax in the Tahoe, Suburban and 1500 · Commercial truck financing
Horsepower, torque, payload and option pricing are General Motors’ published figures as of October 15, 2026; tow ratings and option content are from the October 9, 2026 order guides and apply to standard-equipped trucks. Monthly payment example is a straight division for illustration, not a finance quote. GM incentives referenced are GM programs valid through November 30, 2026. Carter Chevrolet charges no documentation fee and no dealer addendum.
Gas or diesel, we will show you both numbers
Same trim, same cab, two payments side by side, with your trailer weight in the conversation. Order a 2027 or drive a 2026 Duramax this week.