Can't say for the 560 (haven't looked), but the 4.5 alternator has a wire that terminates in a black cube also. That cube is bolted to the center of the backside of the alternator (if that makes sense). No idea what it is, I just know I had to attach it when I did the alternator swap earlier this year
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.