A retrofit is the installation of a safety or monitoring system on a forklift already in service, rather than buying a truck with the system fitted at the factory.
Many sites add detection, speed control or telematics to an existing fleet, often a mix of brands, models and ages. Warning-only systems, such as tag ranging units, cameras and lights, retrofit to nearly any truck because they need power and a mount but no control connection. Systems that slow or stop the truck need an interface to its controller, usually through the CAN bus, so they work on compatible forklifts and may need a different kit or a warning-only setup on others.
OSHA 1910.178 does not allow modifications that affect capacity or safe operation without the manufacturer’s prior written approval, so anything that changes the truck’s controls, adds weight or blocks visibility should be checked with the manufacturer or dealer. Practical points to confirm are mounting that does not block the driver’s view, wiring that survives vibration and washdown, who maintains the hardware, and how the system behaves on each model in the fleet. The retrofitting guide works through a mixed fleet.