whata waste of 39 posts .
rocks are (usually) under a vehicle so Rock sliders (to slide over rocks) need to be underneath the vehicle.
trees are (usually) not under a car but to the side, so tree sliders need to be on the side. It doesnt matter high high up the side, but most peeps have combined sliders - tre & rock sliders) and it is cheaper to manufacture them together, hence both are fitted at sill level.
rocks are (usually) under a vehicle so Rock sliders (to slide over rocks) need to be underneath the vehicle.
trees are (usually) not under a car but to the side, so tree sliders need to be on the side. It doesnt matter high high up the side, but most peeps have combined sliders - tre & rock sliders) and it is cheaper to manufacture them together, hence both are fitted at sill level.