axle question

pulled the axles and rearend out today. was surprised to find that it has a 3.23 open in it. looks like I am going to have a 3.23 ring and pinion for sale now. Bearings are shot. has a lot of play in them. will go back with either Green or Moser sealed bearings. but I saw a plate in the housing that isn't in my Duster. what is it for, does it need to come out. picture isn't he greatest but you get the picture. it is thin metal plate just inside the housing end.