Pretty confident you've got an 87 there.
Mine is an 88 and has the chain stay U brake.
I got mine for $30, frame, fork, headset with no bearings, both brakes and levers, and that's it, nice steal there for 25$ complete!
Looks like the 87 came built up a lot nicer than the 88 as well, though I never saw mine in its original condition, I do have a few of the original bits, and they're all hideous matt black rubbery Shimano Exage stuff.
From what I recall that stem is originally black and tends to fade into orange and ever lighter when left out in the sun too long, fade it a little further!
I really love that black chrome finish, its so damn pretty.