I've seen various posts here regarding rear air bags and the need. I can share that our truck has just over 300,000km on it and still runs like a top. Lots of preventative maintenance, but no issues. We'll get a new one in the next few years but good for now. We towed a 30' Laredo for 5 years or so. The truck/trailer completely level when loaded. Not so with the 337 as it's a bit more nose heavy. Had a bit of sag with it, so put in a Firestone air kit on the rear axle. Unbelievable how much better it rides! With the trailer on, the bags are at 25lbs to level it. The ride though is so much better. Previously, the ride could best be described as harsh and rattly. Much smoother and quieter with the air bags. Interestingly, the quieter, smoother ride generates a higher level of confidence in the whole set up. Even unloaded and at 10lbs the ride is much smoother. Should have done this years ago! Without a doubt, as soon as we get a new truck, it'll be getting an air bag installation.