Shimano STX question.

[Drengelus]

Hello everyone, new to the site. I had a big question about a bike I bought used a few days ago.
The bike was pretty beat up, but my biggest question is about the broken rear derailleur. I searched the net for the exact model (Shimano STX RD-MC32) and only have come up with used parts on ebay.
I am not too keen on used parts, since I don't really know how beat up they got, or how much stress was put on them in their lifetime.

My question is what can I replace this with? The bike is twenty-one speed, three on the front seven in the back. I think it's a long cage and 10 tooth on each cogwheel.

[Painkiller]

if that is all you want is a rear derailluer, and do not care if it is stx or not. Most any direct mount 7/8 speed will work. depends on what you want to spend.I have a nice one for $35 + shipping but you may not want it because it is used and been sitting in a drawer since around 1995. RD-mc31. The vintage stuff commands pretty good prices so just go with an 8speed newer style
on the cheap:
http://www.amazon.com/Shimano-Acera/dp/B003UWJW7W/ref=pd_sbs_sg_2
a little better:
http://www.rei.com/product/753543/shimano-alivio-rm410-rear-derailleur

[nfmisso]

I am cheaper than PK - his suggestions are very good.

I would go with:
http://www.amazon.com/Shimano-Tourney-TX55-Speed-Derailleur/dp/B003ZM9RDQ/
or if you need one with a hanger:
http://www.amazon.com/Shimano-Tourney-TX55-Speed-Derailleur/dp/B003ZMBNG0/

I have one of these on my World Tourist with thousands of trouble free miles on it.

Make sure you install a new chain, and make sure that your freewheel or cassette is in good condition.

[Drengelus]

Thanks for the replies guys. I can tell you looking for one on my own was just, oh so confusing. It was starting to drive me bat crazy! Thanks again for the links and replies