Is it safe to buy a truck that has been sitting for 3 years but has low mileage and runs?

Any used car bought better undergo an inspection by a trained mechanic. There are a slew of parts and systems that can go wrong simply if the car has been sitting for three years. Was it sitting in the sun or inside a shaded area? what is the condition of all the rubber parts, hoses, boots, belts, ignition cables, brake system and tires? Oil and water must be checked also. Oil can deteriorate and water can rust the water pump while car is sitting. Need to look for rust signs. A trained mechanic can check your engine and and give you a better answer regarding engine and transmission.