242 and 231 outer case differences?

I'm wondering if the cases of the 242 and the 231 are the same and just have different internals. I tough i read or been told somewhere that the 242 and the 231 have the same outer case and just the insides are different. I bought a np231 for ten dollars today and the part of the housing, under neath where the studs are to bolt to the tranny, has a long crack. I do have 2 spare np242 that i could take apart, and if its possable use the outer case to fix the np231. i have an 88 xj with a np242 and i would like to change to the np231. If anyone knows anything about this would be great to hear. I cant rememeber where i heard this from but i would like to clear this up for me.

for get about this. i grabbed one of my extra 242 and put it next to the 231 and it is very diffrent. im gonna figure out how to delete this and do.

i cant figure out how to delete my thread if a admin could delete this that would be good