Two issues with my H2
 

My first issue is when changing gears or leaving a stop light I hear/feal a slight clunk.
Kind of like when a universal joint is wore out, I crawled under the truck and shook the crap out of the front and rear drive shafts and there was no wiggle/slop.
I'v only owned this truck for two days so I don't know much about them.
The other thing is when I first start the truck the odometer section says service air suspension.
The guy I bought it from said it was a sensor that the dealership was going to charge $700 to fix and it never seemed to affect anything so he never got it fixed.
I just push the button to show the odometer again.
What sensor would cost $700 to change?