In 1984 the Simplex Delrin was far less common than in 1970 (most had broken?), and even Simplex was bringing out aluminum parts. In 1984 the 600 Arabesque had morphed into the smooth and sleek 600EX, marked 6207 on the back rather than 6200. My '84 Trek 610 came with that one, and I never liked it. Now I'm using the rear mech and the crankset on a UO-8. It's not bad on there, but I don't expect any good rear shifting. The derailleur was not better than what else was around, due to the Sun-Tour design and Campy NR and SR for narrower gear spreads. But I lived with all that, and it's just fine on the UO-8.

What I really didn't like were the side pulls and the cheap levers - way too much flex and poor braking. I replaced my uncomfortable levers with a set of final-markdown Modolos, and the flexy Shimano cables with a set of Modolo (or Campy?) cables with super-thick inner cables. I filed the ends of the outer cables to be truly square so they would with stand compression without bending and twisting. The squish was nearly gone after all this except for the caliper flex which was a lot more than the Campy side pulls of the '70s. A pad replacement with salmon Kool-Stops improved braking power, and I use this setup to this day, at least in the back.

I don't have hate for early '80s Shimano, but I have not-all-good experience.

Oh yeah, my '86ish Mondonico came with 6207, as well. Original buyer of the frame was a grad student who wanted to race. So I've had it on two bikes bitd.

I'm still using the downtube shift levers and the front mech. Those are quite nice.

Overall pretty stuff, but not all of it was very functional.