Equipped with new Tier 2 Cat 3046 engines, D3G, D4G and D5G track-type tractors produce 70, 80 and 90 horsepower, respectively. They are market leaders in each of their size classes, Caterpillar says. The machines have more standard features including two 12-volt 900 CCA batteries, a turbine-type precleaner, 110-amp alternator, and air-intake heater. In addition, Cat is offering the factory-installed AccuGrade Laser Grade Control System. Other options include Cat's Product Link System, hydrostatic winch with infinitely variable line speed, and a rotating bushing track on the D5G. Estimated list prices: $74,000 to $120,000.