Sorry for the confusion... I actually did mean the Getrag brand (not the "transmission" brand! :oops: ) I looked through some old literature, and it appears that even the Getrag is incorrect. Mercedes used their own 5sp transmission as the successor to the ZF.
As Chad has mentioned, Mercedes came out with their own 5sp transmission in the late 60's/ early 70's and these mostly went into 114's, and later on, in the 123's. There were also a few 280se 111 coupes fitted with 5sp transmissions for European delivery (mostly the Mercedes side-loader).
Back to your question, the S5-20 is certainly the ZF 5sp. However, I'm unsure whether the G76 is the Mercedes' own brand, or made by Getrag (which, incidentally, were commonly found in BMW's).
WAQAS in Austin, Texas