I saw that one on EvilBay too. If the top plate is removable on my JP6, I sure didn't know it. Hopefully someone smarter than me can chime in here before I break my JP6 trying to pull that plate off.
It looks like a piece has been removed. I guess I didn't know that could be done. I did look underneath the bridge and there are a couple of screws that appear to hold that top plate on. I just don't know why anyone would remove it.
Maybe the seller can give you a better photo that shows the "Music Man" stamp on the bridge.
yeah, that plate covers the saddles and adjustment screws. you pretty much have to take the entire bridge assy out in order to get that off properly.
i wouldn't do that though. it just makes the screws and strings vulnerable. i only do that when i clean my bridge from all the gig junk, but it's a BOOOOOOOIIIIICH!!!!