Funny that this got brought back up today as I also replaced the rear differential fluids today... But it was an all day thing for me as I replaced the Front Diff, Rear diff and transfer case fluids as well as the Automatic Transmission filter and fluid in My 2003 Jeep Liberty as well as changing all of those in my wife's 2004 Jeep Liberty. I also Changed the rear differential fluid and manual transmission fluid in my "spare car"- a 2002 Jeep Liberty (it is 2WD) The Libertys have no drain plug on the diff covers either, so I had to pull them, they also don't used a formed gasket for the diff covers (or for the Auto tranny pan either- which is odd) so I had to use RTV. I have to do this about once every 2 years to each of these Jeeps (Jeep specs 30,000 miles or 24 months for all of these fluids (and the tranny filter) both my wife and I put about 12-15K on each of our Jeeps a year, so I just do all three about the same time every 2 years (the spare Jeep only got driven 8,000 miles since I changed the fluids in 2009 but I went ahead and did it anyway so they were all done)...but it made for a LONG day today!