The copper washer is only used on certain adapters, 95 & earlier, I don't know the adapter part numbers.
The washer goes between the bolt head and adapter.
I think the way to tell is if a o ring is on the bolt and inside the housing where the bolt goes in, no washer.... But I don't have a...
I have wanted and needed more space for years. I'm trying to get this new shop finished while I'm waiting on parts at the machine shop for the 4 in house now, a few more folks are on hold due to space.