Originally Posted by bartamos
It really boils down to RPM vs rigidity of the shaft.
Bingo!

For some reading on he subject try the Spicer Driveshaft Applications Guidelines
found linked in this tech tip
http://www.stovebolt.com/techtips/driveline/setup/index.html

You can have a long driveshaft if the RPM is low enough and the tube diameter is large enough... along with some other considerations. Figuring out what is safe and reasonable takes some head scratching and or expert advise, like from a driveshaft shop and the Spicer literature.

Sounds to me like a two piece shaft will be the safer option, but worth running the numbers and investigating all options.

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