what's involved in a differential swap??

[j.fro]

I'm getting my 1999 996 C4 back on the road and was thinking about taking the Guard torsen diff from my Boxster S 6-speed and swapping it into the 996 trans. I know that I need to keep the 996 ring gear mated with the original pinion. I'm wondering what's involved with the diff swap. I've done diff swaps in a Chevy rear where there was lots of assembly/dis-assembly to get thing shimmed right for the gear lash. How about for the Porsche Getrag trans??