DETROIT (AP) _ Chrysler Corp. says it has launched production of a 3.9-liter V-6 truck engine, which will be optional on the company's Dodge Dakota pickup truck.

The engine was made by cutting off the front two cylinders from 5.2-liter V-8 truck engine, the company said Monday. Using an existing engine block allowed Chrysler to develop the engine for $70 million.

Because the engines share a block and components, Chrysler will be able to switch production easily from one to the other depending on demand by customers, Chrysler said.

The engines share a water pump, rocker arms, tappets, pistons, valves and springs, crankshaft and camshaft gears and connecting rods and are made at the company's Mound Road engine plant in Detroit.