Also, looks like the seat is pretty far aft. I don't know about the early Blazers, but in my 88, the seat is very close to the dropoff since that's where your feet go. My seat would latch to those except my stock latch bars are sunk into the floor.
What I'm getting at, is it looks to me like possibly someone took a seat from a later K5, mounted the seat a little farther back and used those hoops to get the latches to work.