the Np 208 is an all in one chain, I havent heard of it being used in that way...
Budget wise.. to get the same gearing as the doubler you could just go with an Atlas II TC. but they are pricey.. (3-4g range) hence the reason i went with ORD's i have literally $150.00 in both the 203 and 205 TC from a local junkyard. i spent about 1g in ORD parts including 3 stick shifters, ( the shifters from ORD are easy to install, the instructions are very detailed,and made installation and adjustment very simple.)
Also had to get input shaft so the 203 will accept the 32spline output from 400. ( 205 is twined stick- highly recommend for the versatility ) this give full range and what all 4x4 should have..lol...The sequence is as follows... far Left stick 203 H-N-L Middle stick 205 ( Rear axle ) H-N-L far right stick 205 ( front axle ( H-N-L ) if you notice in 3rd picture im currently in 2 rear axle high.
I also spent another $450 in getting 3 custom 8" slip 1350 driveshafts made. ( using the orginial front Doublecardan shaft ) it works out that the front and rear drive shafts are so close in length, i have a complete 3rd i keep in CUCV as a Spare if needed. i also used a 2nd crossmemeber from a civil K5 for added support... I dont like the way however its currently mounted. and plans are in works to completely redo the mounts and do away with using factory crossmembers.