Roger, This one is "ol' # 4". Long story. With extensive and frustrating checks and double checks of the radio components and each time everything checked out I might add, it took my first two UCD's to find out that I had an intermittent glitch. OUCH! Both had engine damage to make matters worse. So........... trashed all the Futaba gear and in #3 installed all new JR equippment, stem to stern. I'm all set, what could go wrong. A dozen flights with the new setup and loving it, the crystal popped out of the RX !!!!!! As anal as I am about this stuff I never knew you should tape the crystal in. Oh well. As far as the tank and CG. On 40 sized craft the center of the tank and the CG are within 6 inches of each other. On this long fuse the center of the tank is now 10+ inches of seperation. As the fuel draws down, I've experienced a good deal of chenge in the CG in flight. On the last three my 5 cell battery was always in the aft. of the compartment. So if it has to go forward its no big deal. Now the only change is the weight of the plane as it burns up fuel. With the tank on the CG you still have the option of makeing the CG as mild or wild as you want. Joe