Hi Ken,

The newer receivers are coming with a sticker that designates whether they are hi or low band, but if you have some that are not brand new, the only way to tell is to get two crystals, and test them out.
You may want to get a channel 11 or 12 crystal and a channel 59 or 60 crystal, use one in the receiver, do a range test and see how well it does, if you are not getting good range, try the high band crystal, you should then be getting a good range test.
Also you might want to consider sending these into the service center to be checked over and tested.

I hope you find this information helpful. You can also reach our Futaba support technical team at 217-398-8970, or via fax at 217-398-7721.

Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician
Also you may want to check our Website at (http://www.futaba-rc.com)