D2 main clutch release Collar

Trying to figure out the correct orientation for the brass collar (front to back).  I am putting a new one in that is slightly different than the old one which is worn pretty badly.  I want to make sure I get the new one in the right way, so as not to cause adverse wear.  The front and back surfaces are not the same, and one is thicker than the other.
this is on a 5U15127, has the newer extended housing for replacing the clutch without removing the engine.  From the parts manual it appears the thicker side might go the back, but not all that clear.