Who makes airbags for the rear suspension of an '03 supercrew that has the rear end lowered 4" with shackles and hangers? There doesn't seem to be enough room for a regular kit now that it's lowered.
I bottom out sometimes with the box full of sailboat fuel (air).

 

I figured it out now. Airlift if one of the few manufacturers to make kits for lowered F-150s. The part number is: 59103