I just pulled my IRS rear unit out yesterday and I am in the process of replacing all of the bushings, the tie rods, and swapping in the 2003/2004 cross brace that bolts to the rear diff. I noticed that there is a weight that hangs off of the front of the differential. I think this is a sound isolator or something similar. I think the other 8.8 solid rear axles had a similar weight hanging off the front. I don't think there is any harm in eliminating it, but thought I would ask, in the even that it has a purpose that I am unaware of. The back of the car feels like it pretty much swims as I cross any lanes on the highway that have any slight groves in them, and any bumps pretty much feel like the car is bouncing left and right, so I am looking forward to getting everything tightened up.