The tailcone on the DC-9 is mostly fabricated from fiberglass. When it comes off, either intentionally or inadvertently, it usually gets a ding (surfing term) at its pointy end which requires a minor repair before being reused.
I think the MD
-80 boattail tailcone is also composite and would get dinged at the lower edge of the boattail when ejected.
The tail slide is mounted at the edge of the metal structure just forward of the where the tailcone comes off and it is deployed manually after the tailcone is out of the way.
There is a narrow catwalk, that gives a tricky access to the slide, with heavy canted curved beams that carry the empennage loads into the fuselage overhead. It is very easy to fram your head into one of these beams. Ouch, ouch, ouch!! The catwalk starts over the APU shroud and the compartment is usually very smelly from skydrol. Experience talking.