I think you’re talking about the door “check” assembly?
#7 in the figure? (2004 parts sheet; likely same for 2006 but double check)
Note differences for left (05104335AA) and right (05104338AA) door.
No idea where to source one; I’d start with Google then at a MB or Dodge dealer?
There are also vans being parted out in the For Sale area of this forum.
-dave