Well, you have to be a little careful. Pictures would help a lot. Almost any old rear derailer will work. Tourney as suggested would be a good choice. If you still have the adapter claw from your old derailer, make sure to keep that. It will help you mount the new derailer. This is an adapter claw: http://www.sheldonbrown.com/gloss_aa-l.html#adaptor

For your FD, you need a bottom pull. It also needs to have the same clamp diameter as your seat tube. There should still be lots of options here. Most old "road" front derailers will work.

[I based the above suggestions on the assumption that this: http://www.trfindley.com/flschwinn_1...983Ltwt10.html is your bike. If that's not your bike, my information may not be entirely correct.]