Replacing a Shimano Rapid-Rise rear derailleur

[Red Tornado]

A friend's son crashed spectacularly and bent both the rear derailleur cage & hanger worse than anything I've dealt with before. Couldn't get hanger straightened back to normal, but that's not the issue here; they're easy enough to get from the shop. The rear derailleur is the hangup. It's Shimano RD-M580 (LX model) rapid rise and after doing a quick Internet search, found they're pretty darn difficult to come by these days. Got a hit for a used one on E-bay. Also saw some posts on other forums saying Shimano discontinued it?
So I may have to settle for used, but there ain't many out there..... Or does that derailleur have to match up with a special shifter? Could I use a regular LX derailleur with the shifter now on the bike? Don't have the shifter model number at the moment but could get it if necessary.
Input/advice is greatly appreciated.

[oldpotatoe]

A friend's son crashed spectacularly and bent both the rear derailleur cage & hanger worse than anything I've dealt with before. Couldn't get hanger straightened back to normal, but that's not the issue here; they're easy enough to get from the shop. The rear derailleur is the hangup. It's Shimano RD-M580 (LX model) rapid rise and after doing a quick Internet search, found they're pretty darn difficult to come by these days. Got a hit for a used one on E-bay. Also saw some posts on other forums saying Shimano discontinued it?
So I may have to settle for used, but there ain't many out there..... Or does that derailleur have to match up with a special shifter? Could I use a regular LX derailleur with the shifter now on the bike? Don't have the shifter model number at the moment but could get it if necessary.
Input/advice is greatly appreciated.

RapidRise, or 'backfire plus', just means the return spring, w/o a cable attached, puts the der onto the biggest cog(lowest gear) instead of the smallest cog(highest gear, cog). Getting a more normal, 'High Normal', rather than your old 'low normal', just means that shifting will be backwards. Thumb button to lower gear, front trigger to higher gear rather than the reverse. But the shifters are compatible with any shimano MTB rear der except 10 and 11s ones.

[bikinchris]

Shimano still makes rapid rise deralleurs. Just not maybe that exact model. They don't seem to sell parts for anything very long. You can use top normal deralleurs to replace it. Like Old Potato said, the shifter will show the reverse of what is happening.

[Ken Robb]

The gang at Rivendell were VERY enthusiastic about Shimano rapid-rise derailers because when used with barend shifters moving either lever up got you a higher gear rather than the normal derailers where you get a higher ring but a lower cog when you move the levers up.

So, Riv no longer lists them for sale but MAYBE they might still have one lying around.

[bmeryman]

Shoot me a PM. I can think of at least two rapid rise XTR rd's at the shop that I'll find tomorrow. I can send one in your direction if you'd like.