Just to muddy the waters further, if you go to HiTec's website and look up support info on their Ranger III FM (75 Mhz Surface radio) they give instructions on how to pull the crystal and change the frequency.
Click on Ranger 3 FM:
http://hitecrcd.com/homepage/nsupport_SFS.htm
I would also point out that the surface people (boats, and I guess cars) think the "you can't change your frequency" thing is an AMA rule. They explain that there's no way they can have a race with 20 boats on the water at once at their Nats unless people can change frequencies. They have a point!
But of course, they can afford to be a bit more casual because a frequency conflict won't crash their boat into the ground from 300 feet up!