The 231 with a HD slip holds up pretty well I've not broke it yet . The Aw4 after finding a clogged line and flushing it runs without issue the fluid stays red and even with a near complete clog and black burnt fluid running trips over Eisenhowe pass it still lives /runs perfectly .Before I found the clog I thought it was the 5600lbs of jeep causing the heat issue so i put a 29,000 btu fan cooled B&M on it , so obviously it runs very cool now after flushing . The drive shafts are basicly what you suggested double cardan 1310 cv at t-case and a hybrid 1310 /1350 yoke ...1310 drive shaft 1350 pinion. If I did not have the need for the longest slip yoke they make I would ditch the hybrid 1310/1350 , but the stub shaft on my driveshaft would need to be changed to use the long 1350 they make a shorter 1350 that works ,but the looong one like the 1310 needs different spline . The hybrids are like $40 a joint which is why I hate them .