Originally Posted by BMW86
I'm not sure on the reasoning. Yours will be welded since yours is a manual. Accelerate Automotive in Coopers Plains did mine. They've done a few now and I had no issues. I'm using redline 75w140Ns, I think. Dropped the diff oil at 3k because I'm OCD. You have the right idea about installing the other components at the same time as dropping the rear subframe is very labour intensive.
Mine is bolted by memory all pre mid 07 were all bolted
I have heard its wise to change diff oil as often as your crankcase if you drive your car hard.
And another excuse to buy all the supporting parts also to do with the diff