91 Prizm left tail light assembly removal.

I know that I'm old but I can't figure this one out. Can anyone tell me how to remove this assembly? I've removed the 2 exposed bolts on the right side and taken the nut off of the brass stud under the trunk lining but something is still holding it on the inside of the left side of the assembly. There is a black plastic [ Stud ] ? sticking out into the trunk over there and also a white nylon [ cage ]? that looks like it's slipped over a small white nylon dowel but I'm not sure what these 2 things are. Can somebody please tell me how to remove them without breaking them [ if that whats stopping me from getting the assembly out? Thank you, sorry that I can't explain it very well but it's really got me going in circles.