This may be one of the jobs that you want to sub out. Torque spec, canoodling with the driveshaft and the mess of it might make it a choice for a good rear end shop that has all the stuff handy. It isn't a particularly hard job if you have all the right tools and the patience. The other thing I will add to the list is you might want to think about using synthetic lube in that diff. Especially on the 220s, with the factory 4.56 gears, there is a lot of wear and tear that goes on in the lube.