BLANCO, Tex. — Narrow McCall Creek Road carves twisty chicanes into limestone embankments which ripple through the rolling Texas Hill Country.

Over this contorted asphalt comes a 2012 iteration of Chevrolet’s Silverado 3500HD — Heavy Duty, the tell-all descriptive for big and powerful work trucks developed by General Motors for the upward expansion of Chevrolet’s full-size line of Silverado pickups.

These behemoth trucks, built on a strong structure that’s modular in design to allow multiple configurations for cabin size and box length, bulge from chiseled sheetmetal styling and ripple with enthused strength due to heavy-duty powertrains that muscle up to the head of the heavy class in terms of raw horsepower, engine torque and efficiency for towing and toting hefty loads.

They also provide uncommonly comfortable passenger compartments in cabs equipped with two or four doors, and can perform tricks rarely seen among work trucks: They’re smooth in suspension ride and downright easy to operate.

Our test truck — Silverado 3500HD one-ton Texas Edition pickup in plush LT trim — has four-wheel-drive (4WD) traction and four-door Crew Cab configuration containing front bucket seats and a rear bench sized for three broad-shouldered adults.

Beneath the high-hiked front hood, this 3500HD Silverado carries an optional Duramax 6.6-liter V8 direct-injection turbo-diesel engine which employs “clean diesel” technology to harness the power of 335 horses.

The diesel plant links to a remarkable Allison 1000 six-speed electronic automatic transmission. A sophisticated transmission control module in the transmission acts to select gears and engage the torque converter lockup.

For towing a trailer like the one trailing behind our rig, this intelligent transmission in Tow-Haul mode stabilizes shifting by automatically selecting an ideal gear after sampling various factors, such as engine speed and throttle position.

On long downhill grades over U.S. 287 through the Texas hills, the transmission control module actually downshifts without driver prompting — from sixth gear down to fifth, then down further to fourth or third as needed.

It drops to lower gears to retard the weighty truck-trailer rig on a downhill slope and spare the big disc brakes from overheating.

In effect, the transmission package erases all traces of effort related to the chore of driving this trailer-toting truck. All we as the driver need to do is grip the steering wheel and keep the prow pointed in the proper lane.

Reducing the driver’s workload becomes an apparent theme for Silverado HD trucks.

In the stretched cab of a deluxe LTZ edition, the high-back front bucket seats are clad in leather with heat and cool elements plus power controls. Luxury components range from power windows and electric exterior mirrors to a tilting steering wheel wrapped in leather, cruise control, dual-zone climate controls and nice audio gear including Bose premium speakers.

In effect, the big truck packs all of refinements of a refined luxury car.

With so much heavy duty work gear aboard and that monster diesel capable of out-pulling and out-powering virtually anything on the road, this particular Silverado HD reminds us of some steroidal body builder scrubbed and polished, then dressed up in a tuxedo.

But Chevy’s HD work trucks don’t all have to be fancy.

With three trim choices and so many different configurations for cab and bed and powertrain and traction, the series consists of a complex array of models that can be bare and simple at one extreme or refined and luxurious for the other.

The series of one-ton 3500HD trucks offers cab dimensions of regular and extended lengths plus the Crew Cab, two traction systems in rear-wheel two-wheel-drive (2WD) or 4WD format, two lengths for the truck box and choices for a gasoline-driven V8 engine or that Duramax turbo-diesel.

GM’s Vortec 6000 6.0-liter V8 serves as the gasoline-swigging plant. Output rises to 360 hp at 5400 rpm, with torque skewed to 380 lb-ft at 4200 rpm.

This engine ties to a heavy-duty transmission with six forward gears.

The Duramax 6.6-liter V8 turbo-diesel engine generates 335 hp at 3100 rpm and incredible torque of 685 lb-ft at 1600 rpm.

There are three different cab styles — Regular Cab (two doors and a bench or buckets), Extended Cab (bench or buckets in front of a back bench with two wide-swing access doors behind front doors), and Crew Cab (a four-door cab with front buckets or bench and a big back bench for three).

There are two different lengths for the rear truck bed — Standard Box (6.2 feet) and Long Box (8.2 feet).

There are two different suspension packages — a Z85 suspension that’s standard on 2WD and 4WD models and the Z71 off-road kit which adds chassis and suspension equipment and underbody skid plates.

And the new Texas Edition applies 18-inch aluminum wheels (or 17-inchers for duallys), a trailer package with automatic-locking differential, dual-zone climate controls, six-way power driver’s seat, power camper mirrors with integrated turn signals, foglamps and EZ-Lift tailgate, plus chrome door handles and six-inch oval assist steps.

The bottom line:  Chevrolet’s 2012 Silverado HD trucks carry MSRP figures stretched from $30,150 to $46,425.

2012 CHEVROLET SILVERADO HEAVY DUTY PICKUP TRUCKS SPECIFICATIONS

• Description: Full-size heavy duty truck
• Model options: 3500HD one-ton
• Trim options: Silverado Work Truck, Silverado LT, Silverado LTZ
• Cab styles:
  • Regular Cab
  • Extended Cab
  • Crew Cab
• Box lengths:
  • 78.7 inches
  • 97.6 inches
• Wheelbase:
  • 133.7 inches
  • 153.7 inches
  • 158.2 inches
• Overall length:
  • 225.0 inches
  • 240.2 inches
  • 249.5 inches
• Engine size:
  • OHV 6.0-L V8/VVT
  • OHV 6.6-L V8 TD
• Transmissions/speeds:
  • 6.0: Auto/6/Shiftable
  • 6.6: Auto/6/Allison 1000
• Rear/front drive:
  • 2WD/Rear
  • 4WD
• Steering: Power recirc. ball
• Braking: Power 4-disc/ABS
• Air bags: 2 (front), 2 (side), + opt. 4 (side curtain)
• Maximum GCWR: 30500 pounds
• Maximum trailer towing: 18000 pounds
• Maximum 5-wheel towing: 23000 pounds
• MSRP range, est.: $30,150 to $46,425