The Gen 3 roof rails taper inward toward the back - enough so that the rail spacing decreases about 3" from front to back, all told.
Thus, the wider crossbar goes in the front. Sorry, I don't know which part number is which, though.
I believe the side clamps allow the horizontal tubes to slide in or out a bit, which is how they can be repositioned when there is this taper in the side rails. Tightening the clamps tightens the tube as well. But I've had my crossbars fixed in place for so long to accommodate my Thule that I honestly don't fully remember how this part of it works.
Thus, the wider crossbar goes in the front. Sorry, I don't know which part number is which, though.
I believe the side clamps allow the horizontal tubes to slide in or out a bit, which is how they can be repositioned when there is this taper in the side rails. Tightening the clamps tightens the tube as well. But I've had my crossbars fixed in place for so long to accommodate my Thule that I honestly don't fully remember how this part of it works.
