Owners of GM Silverado 2500/3500 HD pickups and 3500/4500 chassis now have the option to electrify their vehicles through a system offered by XL Fleet.

The XLP plug-in hybrid electric drives build on existing vehicle platforms, combining electric motors and the existing powertrains that run on internal combustion engines.

At the heart of the system is a lithium-ion battery pack and electric motor that mounts on the driveshaft. A plug-in charging port at the rear bumper can take power from J-1772 Level 1 or Level 2 chargers.

The electric motor will feed 220 lb-ft of torque into the driveline as the vehicle accelerates, reducing engine strain and gas consumption alike. When decelerating, that same motor turns into a generator to feed the battery pack through regenerative braking.

The system mounts under the chassis, leaving the Silverado’s bed free and clear.

It’s all available on the Silverado pickup trucks with a 6.6-liter engine and 4×4 driveline, and at least a 149-inch wheelbase. And it can be added in any bed size.

Since everything is mounted after the transmission, GM warranties and service schedules are unchanged, the company says.