BB i`ve come accross this before,
there two types of crystals for hitec and futaba,
single conversion and dual conversion,
single conversion have a green tag on teh crystal whereas dual has a blue tag.
unfortunately they are not cross transferable, so a single conversion wont wor in a dual conversion reciever,
try checking your original crystals to check teh colour on the tab, if thats no good check teh hit website and look up your receiver to see which it`s compatible with.
www.hitecrcd.com
hope this helps.