Base engine in most models was a 4.3-liter V6, rated at 160 horsepower. Three gasoline engines were available: 5.0, 5.7, and 7.4 liters, making 175, 210, and 230 horsepower, respectively. The 7.4-liter V8 was limited to heavy-duty C/K 2500 models. Also available: a 6.2-liter diesel, at 140 horsepower. The 4.3 V6 gained five horsepower for 1993. A C/K 2500 rated over 8500 pounds GVW could have a heavy-duty V6 with slightly less power, modified for hard use. By 1994, twin 6.5-liter diesels ousted the prior 6.2-liter, available with or without turbocharging. Horsepower got a big boost for '96, as V6 and V8 engines adopted a Vortec designation. The normally aspirated diesel disappeared, but the turbodiesel remained available. A 5-speed manual gearbox was standard on most models, though earlier examples might have a 4-speed. A 4-speed automatic transmission was optional. Insta-Trac part-time 4WD had automatic-locking hubs and shift-on-the-fly capability.