Originally Posted by madamstn
...I also noted you mentioned using solid shaft instead of tubing. Bad idea...
If you do it right I believe a smaller shaft would be better. It would be nice to have it gun drilled for weight reduction but that is not necessary. What you would end up with would be a long solid shaft that is splined on both ends. Something similar to a half-shaft (which sees more torque than a drive shaft because of gear reduction). It would act like a torsion spring helping to absorb things like clutch drops (that a tubular drive shaft would not). The key is that it would have to be made right and that doesn't come cheap.