I say on "trucks" one time that they put a rear air suspension on their 1 ton. I don't remember who made the system though. What I liked about it was that is had a very small leaf spring and that all the heavy lifting was done by the air bag. I liked that idea because it didn't need an expensive 4 link. The kit was also 1000-1300 dollars with the compressor. I have tried Google and can't find it.

never mind I found it.

link

It was literally like finding a needle in a haystack.

I thought you meant kelderman. They build lift kits for fords with air bags.