Ok, maybe it's just too early but I researched and am still confused. I have an old RD-7400 on my sweet Antares. But the resin pulley wheel is cracked and the seal between the pulley cage is gone and the other seals are shot. Do I have to replace this with another RD-7400 or can I used a RD-7401 or RD-7402 SIS derailleur? Seems to be easier to find good condition 7 or 8 speed RDs than the 6 speed and I don't want to buy another RD-7400 just to wind up with bad seals again. And the index shifting was working so nicely before I had problems so I want to keep that sweet shifting going.

Here's a pic of the shifters:



thanks!