Here is a thread I saved a while back about the NP231.
http://www.pgh-offroad.com/forum/showthread.php?p=89437There is some great stuff about using the Chevy and Dodge versions to beef up the Jeep version. There are a few actual facts in the write up like the NP231 can handle 1940 ft/lbs of tourque!!!! and the NP242 is in the 1400ft/lb range. Out of 25+ posts, the only chain breakage was a worn out chain. There are a few guys that managed to explode them, but under pretty stressfull situations, but the D300 are known for exploding under high stress situations.
For the $$$ I don't think the NP231 can be beat( my opinion). If I had the $$$ I would put an atlas in, but then the t-case would be worth almost as much as the rest of my Jeep
. For the trails we run, I don't see any NP231 t-cases breaking unless something else like a busted spring/ control arm/ rock etc... causes it to break.
By the way the avitar for post 25 and 26 are worth checking out even if you don't care about the NP231
By the