Tom, the two pieces that are an addition to the stock liftgate install are these two upgrades.
The first is expanding the control switches to have one on each side of the liftgate instead of the single clumsy big yellow control.
Mianne Lift Gate Control Expansion
The second enhancement to me was a major improvement in reliability of the lower limit switch. When you see the lame toggle switch and angle iron limit switch that comes with it, it's easy to see why they can get out of whack easily and cause a major issue with the cable unspooling. This only has to happen to you once to realize it's a big problem!
Mianne Lift Bridge Lower Limit Switch Enhancement
Finally, here's the diagram of the stock liftgate servo system for the curious.
