I wouldn't buy a Futaba receiver. Reason - price.
The Hobbico 7 channel receiver is a Futaba with a different label and it is only 50 bucks with crystal.
http://www2.towerhobbies.com/cgi-bin...I=LXLN98**&P=0
The Futaba equivalent is the R127DF and it is $65 plus $13 for the crystal.
I'm no receiver or crystal expert. I know you should always use the crystal that is recommended for the receiver. For example, Hitec makes receivers that are compatible with Futaba transmitters. You use a Hitec crystal in the Hitec receiver.