hypothetical question: what would happen if you had the crv k20 transmission connected to a wagovan 4wd diff with a strait custom drive shaft drive shaft , no viscous coupler , would the diff be engaged at all times ? or would the whole drive chain just explode ?

 

Correct, you will have binding in that configuration leading to the finding of the weak link. Probably the transfer case bolted to the transmission.

You need something in the system to allow the front and rear axles to operate at different speeds.