I still have my old Hitec 7 with the dial a crash module, it's a pretty good radio and can be converted to 2.4 with a new module. I changed over my Futaba 9-C with a new hitec 2.4 module but I got the module on a special deal for $20.00 a few years back. I tend to agree with Jester though and wouldn't be buying old radios, it's not money well spent when you can buy a nice new radio on 2.4 and it will come with a RX. Pull up Aloft hobbies and see what they have to offer. I just bought several of there 2.4 8 channel RXs and they are less then half the price of the hitec receivers and work very well.
The only reason I have hung onto my old hitec radio is for a back up. To give you an idea of how the prices have gone down on old radios on 72, the dial a crash cost me almost $100.00 when new.
I didn't bother using it often in my Futaba, yes, they work on both Futaba and Hitec. I just stuck with my Ch 15 module and bought new ch 15 crystals for all my other RXs.
Pull up Aloft and look at there radios. Why buy old and waste your money.