The numbers told the story: 97 cents a gallon for unleaded regulargasoline versus $1.09 for diesel. What you give up in power, you make up forin mileage-but pay a dime or more a gallon for the ability to travel fartheron a gallon of fuel. We test drove the 1992 full-size Chevy Fleetside pickup truck with turbodiesel engine, a vehicle more suited for the trucker aficionado than thecasual observer, the person who needs a workhorse and not the person simplylooking to make that 500-mile trip on one tank of fuel. Those simply looking for a once-a-week stop at the corner station or non- stop vacation without refueling helped spoil the diesel image when he orshe found that a diesel needs to be driven for it to work properly; that theparaffin in diesel fuel congeals in cold weather, which can make December-February starting a nightmare; that diesel fuel foams when filling the tankand tends to shoot back onto your hands at the fuel stop so you carry thesmell with you all day. In the `70s, with fears of oil shortages and anger over high gas prices,many consumers turned to diesel engine cars for their low-cost, high-mileagefuel, only to find it wasn`t the liquid of choice for 10-mile-a-day commuters in business suits. When consumers started swarming to diesels, filling stations convertedone pump from leaded or lead-free to diesel, and getting a tankful was little or no problem. You didn`t have to rely on a truck stop along the interstate tobuy 10 or 20 gallons for your Olds, Buick, Volkswagen, Mercedes or Peugeot. As the fad lost its luster, the filling stations converted the dieselpump back to lead-free. Finding the fuel is a chore unless you live on aheavily traveled truck route. We pulled into a truck stop for $5 worth of fuel, luckily just ahead of a few semis in the hunt for filling 50-gallon tanks. Had we arrived a fewminutes later, we would have been sniffing diesel exhaust for several minutes while the truckers were topped off. The Fleetside is a real pleasure. It offers car-like room and comfort,and any amenity you can put in a car can-and usually is-put in a truck. Turn the key and you snap back to reality from the racket coming from the engine at startup. There`s enough insulation in the cabin so you don`t have toput up with as much of the diesel engine ping-ping-ping as you did in the`70s. And the stereotypical black clouds of smoke belching from the exhaustseem to be a thing of the past. But don`t waste your time waiting for theengine to purr. The 6.5-liter, 190-h.p. turbo diesel is new for 1992 and available onselected C/K 2500 and 3500 series trucks with a gross vehicle weight ratingabove 8,500 pounds. The 6.5 turbo diesel V-8 is teamed with 4-speed automatic transmission. The 6.2-liter, 150-h.p. diesel continues to be offered forlight-duty trucks under 8,500 GVW. The 6.5-liter turbo diesel is part of a $3,100 option package thatinclude s twin batteries and an engine block heater. The four-wheel-drive Fleetside pickup we drove has a base price of$17,148 and includes such standard equipment as power brakes with rear-wheelanti-lock (with the weight of the diesel up front you learn to brake a bitsooner), power steering and AM/FM radio. Other than the turbo diesel option,the test vehicle added a sliding rear window ideal for interior ventilation at$130, bedliner at $225, 4-speed automatic with overdrive at $890, heavy-dutytrailering package at $210, a full-size 16-inch spare tire at $334 and chromedrear-step bumper. Also added was a preferred equipment package at $2,485 that included airconditioning, tilt steering, cruise control, upgraded radio with cassette and digital clock, auxiliary lighting and stainless steel exterior mirrors. Thetruck came in at around $24,000.