I have an 88 and a 94 XJ, both with 242s, so my knowledge of yours is limited. I use RockAuto for almost all my troubleshooting efforts. I looked up a 96, which does list the 4370N, and by clicking on the part number, it brings up the years and models that used it. Seeing that it stopped at 96, and knowing that the later models had the bellows seal, I pulled up a 99 and noticed that the OD of the seals for that year where slightly larger than for the 96, thus my suggestion to take a look at those years. It's listing Timken 710663 for the 99.
While a "shorty" SYE will replace all these parts we're discussing, a H&T on these later models doesn't affect the seal, it's all external to the case, unlike the earlier models. There's limited benefit to a full blown SYE on a late model 231 in an XJ. Significantly more torque/HP, extreme lift, short wheelbase (Wrangler), it would have it's benefits, but relative stock under the hood, reasonable lift height (4-8") in an XJ, your money may be better spent elsewhere, IMO... A H&T can be done now or later, I guess it depends on whether you were planning to use lathe or doing it in-vehicle...
If you know what parts to keep paired up (gears for example because of the angle change), you can put any internals with any year case with any year output extension housing... The tag is a good starting point but at the end of the day you have to work with what you have..