The 2027 GMC Sierra HD dieselis getting more expensive, and buyers need to separate two different numbers before they order one. The new 8.3L Duramax is an $11,400 option, and the complete 2027 diesel truck rises $2,310 over its 2026 counterpart on most 2500HD Crew Cab 4WD trims.Where the $2,310 comes fromGMC's comparison puts the outgoing diesel charge at $9,990 against the $11,400 replacement, a $1,410 increase to pick the Duramax over the gas V8 on trims that offer both. Add a $900 bump in the gas-engine MSRP and most diesel Crew Cab 4WD trucks climb $2,310 year over year. The Pro, SLE, SLT, AT4, Denali and AT4X each take that $2,310 hit. Denali Ultimate is the exception: it is diesel-only, and GMC lists it climbing from $96,995 to $99,395, a $2,400 bump.2027 diesel pricing by trimBased on GMC's supplied MSRPs for the 2500HD Crew Cab 4WD lineup:Pro: $68,895SLE: $73,295SLT: $80,595AT4: $87,595Denali: $90,295AT4X: $100,595Denali Ultimate: $99,395The diesel AT4X crosses $100,000 at $100,595, landing above Denali Ultimate, which is diesel-only at $99,395. Each trim is built around a different priority, so the price order on its own won't tell you which has the gear that matters for your use.What the 8.3L bringsThe 8.3L Duramax takes over from the 6.6L as the available diesel, rated by GMC at 555 horsepower and 1,230 lb-ft of torque. The enhanced gas V8 is rated at 412 horsepower and 472 lb-ft, so there's plenty to weigh on either side of the gas-or-diesel call. Beyond the engines, GMC says the HD line picks up electric power steering, an eBoost braking system and bigger front rotors. The AT4X adds larger DSSV dampers and a new Terrain Mode. The pricing material leaves open whether destination is included, and it doesn't spell out the bed configuration tied to each figure. Nail down those specifics, along with options and dealer charges, before you treat any of these MSRPs as a full purchase budget.