Got an 05 GMC Sierra 2500HD. This is gonna sound really weird, But when I drive the truck and park it for a short period of time, My back end seems to sag “ Kind of like that Cali lean crap “. I also notice when the truck is parked for a period of time “ An hour or longer “ It seems to level out. It may sound crazy, But I’m being serious. I’ve never heard of any vehicle doing this. Any ideas why?