A great deal is going to depend on the year and driveline of your car. For example:
The 1994-1995 E320 is the W124 body and the M104 engine. It is OBD-I.
The 1996-1997 E320 is the W210 body with the 1996 car having the four speed automatic and the 1997 having the five speed. Both years are the M104 inline six, but I understand there are changes to the EFI system along the way. These cars, and those after are OBD-II
The 1998-2002 E320 is the W210 body style with the M112 V-6 engine and the five speed 722.6 tranny.
The 2003- E320 is the W211 body style with the M112 V-6 and 722.6.
There are too many forms of "E320" for anyone to be of much help.
1998 C230 "Black Betty"