You Like Complicated Drivetrains? Douglas XB-42 Mixmaster!S

Putting engines in the wings of a great big bomber- who needs all that extra air resistance? Instead, put a couple of Allison V12s inside the fuselage, then have them drive contra-rotating propellers!

What could possibly go wrong? One shudders to imagine the nightmarish assortment of gearboxes, driveshafts, and balance weights necessary to make this Rube Goldberg contraption hold together in the sky, and that's before you even think about how the engines were cooled. We don't worry about practicality with such an incredible exercise in engineering madness, however, and thus the Mixmaster gets our most emphatic Jalopnik Seal-O-Approval™ stamp.
[Wikipedia]