Here's what looks pertinent for you from the table of contents:
-Removing and installing differential
-Dismantling and assembling differential
-Adjusting drive set
Skimming through the sections, it appears to me to have the specifics you would need.
As far as the specific manual, this is the exact manual I purchased: Porsche 911 Carrera 4 And 2 964 Models Series 1989 - 1993 Car Workshop Manual / Repair Manual / Service Manual download - Download Documents / eBooks
I have a G50/05 from a 1992 911/964C2. This manual covers G50/03, G50/04, G50/05 and G50/10 (along with G64/00, G64/01, and Z64/00...the C4 all-wheel-drive models).
If you find the exact manual for your G50/01, be sure to post a link here. I'm sure others are looking just like you. I literally spent hours—probably six or seven at least—trying to find a manual and was just about to give up when I located one.
Even though I can't point you to the exact manual you are looking for, I hope this helps.