This thread is now open for Guessing...
Hmmm, chain drive from the secondary to the rear axle, has an alternator built into the carriage. But doesn't show where it drives from, but I would guess off the jackshaft that goes from the engine to the primary. But where does the 4WD take off from? What is the purpose of the large bodied section between the secondary and the chain drive, could it be a rotary fluid drive pump for driving a front axle?
Just guessing... looks like some good engineering going on here...