Rear Object Sensors / Parking Assist

[solder]

Speaking of nice features we got screwed out of (ala the rearview camera), the service manual mentions a UD7 option which came with a Rear Object Sensor - Left, a Rear Object Sensor - Right, and a Rear Parking Assist Control Module (replaces the Pedestrian Alert Sound Module).

Can we just buy these parts and swap them in, or would it be better to just use an aftermarket (generic/universal) kit? Anyone have any experience with these?