I'm considering trying to hunt down one of these and build it. I understand it's not in 4wd all the time, that it only engages when the front wheels slip, blah. My main question is about the transmission and driveline. Is it the transaxle/transmission, then a transfer case, then a driveshaft to a rear differential like conventional 4WD's? Or is the transfer case built into the transaxle on the front?

 

the transfer case is built into the transmission. the trans is 4wd all the time, what makes it "2wd" is a viscous coupler between the front half and rear half of the drive shaft.