Quote Originally Posted by Toy4Rick View Post
In my case, the fabric is 2" above the slide T rail and if the slide mounting bracket were in the lower position (down 1") the fabric would sill not touch the T rail, see the 2 yelo lines

If it were me, I would try the factory mounted rail and if it doesn't work then install a new rail above...

YMMV
Good luck
Yes I remember reading the instructions and these toppers have two possible heights on the roller end. I will take a close look at the options when I get to this project. We currently have slide toppers recommended by GD which are junk, Carefree Alpine. They recommend them because they have a short mounting bracket needed for the dining room slide which has the awning mounted to the slide on the Reflection 337. We have never been happy with the toppers. They only have one spring instead of two, the fabric was lighter weight and wore out in three years and the anti billow device is built into the rollers and bangs and makes noise and just does not work well.