Ours came installed from the factory. Front two bolts in the first cross member straddling the frame rail. Rear bolt in the rail. If trim is in place holding up the coroplast, you’ll have to trim that back.
They used self tapping bolts that did strip out one of the holes in the cross member. Backed with a nut. Careful on the frame rail without accesss to the back.
Finally got around to adding front stabilizers, I went with Libra. Not much room in the front to mount them but made it work. A lot less Inglewood, we are out next week so we’ll get to see how well they work.