You would not believe the drive shaft angles that my Jeep goes through when flexing offroad. With a Klune-V 4X mutiplier that makes low-low at 10.88:1 (2.72:1 Low X 4) there is an
unbelievable amount of torque being applied at even extremely low speeds.
U-joints and CV joints were invented to handle non-straightline driveshaft situations.
The angles that we are looking at on Backdrafts are so small as to be inconsequential.
Look at the pic below of my Cherokee, if you want to talk driveline extreme angles.
Cheers!
Dave