Hey Donny,

I got a Shimano RSX 8 speed deraileur for mine off EBay for $10.00. I also got a RSX front to match the rear deraileur for ebay for 10.00 also. You can use a Shimano Sora, Tiagra, 105. But higher end Deraileurs like the DURA ACE and Ultegra 10 speeds will not work. There are to narrow and the 7 speed chain will not ride right through the deraileur. So must 7, 8, 9 speeds will work just fine. Now if your going to keep the triple crankset. Then you'll want the long cage deraileur as well. The short cage will not have a long enough movement in it for the triple crankset.

Hope this helps you get a better ideal want you need.