For the older ones (the non-lock and fold), there's a bracket that's bolted to the side that has pins the seats slide onto. It's easy to take out the seats and it usually takes a minute or two fighting the pin alignment when putting the seats back. The bracket is held in place by two bolts. When the seats are not present, the pins overhang about an inch. Seats can be set up forward or backward facing. They are high back, so do not have a removable headrest.
If you're also installing seatbelts, you'll need to put a bolt in the middle of the floor between the seats. Since the seatbelts need to pivot on the bolt, it's not some that can be made flush very easily.
I have these installed in my 110. Let me know if you want any more details.
"Every normal man must be tempted, at times, to spit on his hands, hoist the
black flag and start slitting throats." - H. L. Mencken