Seems like it was as easy as said there, I did mine years ago, the '80 was a totally plastic plate with no steel except brackets, I went Junkyard scouring to find the earlier stouter all metal plate. Cover comes off easy IIRC.
I don't have the rear seat at all, dumped it. Let plate come down flat and with two flaps outboard of the drive tunnel hanging from front of plate then makes an excellent double cubbie hole to quickly hide things you want in car but nobody busting window to get at them. Out of sight, out of mind.......... ....planning someday to raise plate vertical and build say clear plexi higher up to make an interior divider to make a/c work much better as well. No need to waste a/c cooling back of wagon there, I treat it like a truck.