after taking apart the 249, i found that i in fact had the "wrong" np231, meaning that the planetary from the 231 wouldn't match with the input from the 249, even though the split for tooth shape was in 94, and my 231 was a 96, and the 249 is a 98. So for shits and giggles, since everything was apart, i threw the 231 input back into the front half of the case, with the 231 planetary, and threw it up under the Jeep and guess what? it fit. I was able to push it up to the point that i did not feel any movement, and that was without bolting anything up. once i bolt it up, i'm fairly confident that there wont be any leaks. I *might* still use a flap disc to take a little bit of the end of the input shaft off, in the off chance that its a few thou too long, and ill have a slow leak.