4x4mm steel u-joint

[simplechamp]

http://www.rc-monster.com/forum/showthread.php?t=20223

Forum member Marvin's thread about his Hyper 9e. He says the center shaft is about 20cm, which is just short of 8" so it may be too long. Even so, you could probably find a dogbone of the correct length from some other vehicle.

I would say the dogbone is the way to go, since it seems to work well for the similarly setup Hyper 9e. There will be some play with it sitting in the drivecups so that when the chassis flexes the dogbone will have some space to move and not get bent. Use small pieces of fuel tubing in the cups to keep the dogbone centered, and being rubber they will compress/flex when needed.