actually you can put the 241 guts into the 231 case.
2 major weak link is the chain and the planetary gears. which when i did my SYE on my 231 and i saw that there's only 3 gears in the planteary gear assembly, while obviously there's other 3 are missing. and the 241 parts can be fitted in there IIRC. also the stock 231 chain is 1" wide, but the 241 is 1.25" wide, which is stronger.
what i know from this, is from im from other forum for the BlaZeR-2 and S-10 ZR-2, in our research that in older S-series (late 80's and early 90's) came with t-case thats called NP-231HD and the "HD" means it does have that full 6 planteary gears and wider chain. if the 241 parts dont swap in, id think a NP-231HD from a S-series can be gutted and be put into the jeep t-case shouldnt be a problem then hopefully.
btw in case anyone dont know, the JEEP and the CHEVY/GMC t-case isnt same as one is 5 bolt, and other is 6 bolt pattern for mounting to the adaptor on the jeep.
i will want to upgrade my T-case someday to strengthen it as im planning to run some 37's with F-250 axles in future, but as is, it should hold fine.