I had them on my half ton, replaced them with air bags. Like IdaD said, the softer suspension in my half ton did not work well with the Timbrens. I don't know if the gap was right but it wasn't a comfortable ride when empty. I had the proper gap according to their instructions but maybe my springs were getting weak because the Timbrens would engage with almost every bump I would hit. This was on my old truck, I went straight to airbags with my current truck.
I had no complaints with the Timbrens when I had my ATV in the bed and my camper hooked up, it was the unloaded ride I couldn't handle.