I installed the Firestone Ride Rites two months ago on our '06 Dodge 3500 dually. The truck sagged just a bit hooked up to our Montana and I didn't like it. I put the "T" on the back of the truck like some of the others on here did, makes adjusting the level easier.
We just finished a 7,000 mile trip to the west coast a couple of weeks ago and adding 50 lbs to the bags while pulling the trailer made the ride noticeably smoother. LOVE the air bags, for us it was a great investment. We have the MorRyde pin box on our Montana so chucking wasn't so much of an issue.