To understand the lineup, it helps to speak the language: "Half-ton," "3/4-ton" and "one-ton" are outdated terms because modern trucks haul far more than 1,000-2,000 pounds. However, we still tend to use these terms. Sierra 1500 series are the so-called half-ton trucks. Just to make things as confusing as possible, GMC sells a light-duty 2500-series truck line, which we might refer to as a half-ton truck because it's based on the 1500 Series. (See separate newcartestdrive.com review of the Sierra 1500 and 2500 light-duty trucks.)

2500HD pickups are what we commonly call 3/4-ton trucks. All GMC 2500HD trucks come with single rear wheels. Their suspensions and chassis are a heavier duty design than the light-duty 2500 series models; the two can be distinguished by the 2500HD's raised hood.

3500-series trucks come with dual rear wheels; these so-called one-ton trucks are commonly referred to as "duallies."

Regular Cab, Extended Cab and Crew Cab bodies are available with 6.5-foot short beds or 8-foot long beds. Wheelbases run 133, 143.5, 153.0, 157.5, and 167 inches long on 2500 HD pickups; wheelbases are available in 133, 157.5, 161.5, and 167.5 inches on 3500 duallies.

Three trim levels are offered: SL, the well-equipped SLE, and the leather SLT.

Engine choices: 6.0-liter Vortec V8, 8.1-liter Vortec V8, and 6.6-liter Duramax Turbo Diesel.

Just as important are the transmission choices: five-speed manual or four-speed automatic for the Vortec 6.0-liter; six-speed manual or an exciting new Allison five-speed automatic for the Vortec 8100 or Duramax 6600. And, of course, two-wheel drive and four-wheel drive are available.

For 2002, GMC has added two new Sierra Professional models; they are designed as extended cab short box work trucks and are available in 2WD and 4WD.