Originally Posted by
Mondeo Man
I followed your generalised link and it pointed to the page below
Read the first line
http://en.wikipedia.org/wiki/Driveshaft 
Hoisted by your own petard
An engineer knows a rotating shaft transmits torque. A gearbox converts torque. The force applied to the shaft is lbft/Nm
"mechanical component for transmitting torque and rotation"
Torque
and rotation = power!
I am a proper engineer. I know what a gearbox does.
You would have done work ON the shaft, you would not have put power in to it, you would have spent power yourself. power is the rate at which energy is used, to use that high school technique of work done is a bit crude.
JAmes.