Most Chyrsler vehicles of that era use Chrysler Spec MS-5931, I think its the spec for the Grand Cherokee, don't know for sure for the XJ. If the WJ and XJ use the same steering system, then its a good guess they use the same fluid.
MS-5931 is the spec for my Neon R/T, I use Red Line Synthetic PS Fluid (it specfically states it exceeds spec MS-5931). Thats a Rack & Pinion System, not sure if the WJ is a Rack&Pinion System, I'd think its recirculating ball like the XJ.
Mopar®P/N 04883077 Hydraulic fluid / Power steering fluid (MS5931)
Newer Chrysler Vehicles, like 2002 and newer, use ATF+4 as PS Fluid. I know, I know, I just said ATF should NOT be used in a PS System. But Chrysler ATF+4 is a super high quality spec ATF that exceeds the specs of any ATF before it, made specifically to address all the problems they've had with their 41TE trans (Its Synthetic so it doesn't burn up). Its more a case of ATF/PS Fluid coming full circle, the transmissions have been demanding higher and higher quality fluid, that they've upgraded ATF to the point that it now meets PS fluid standard. Thats for ATF+4 only in the later Chrysler Vehicles designed to use ATF+4 as PS Fluid, that does NOT mean ATF+4 can be used in any PS System, I've even some fools make the logically fallacy jump to assume that since ATF+4 can be used in some PS systems, therefore any ATF can be used in any PS System, WRONG. I think Chrysler has a TSB out specifically warning NOT to retrofit ATF+4 into older PS Systems. As well, there is speculation that ATF+4 is barely adequate a PS Fluid, that its being used as a cost savings measure in the PS Systems and Manual Trans, (its synthetic, so that may be why it holds up in several different applications). Several people have reported that they have replaced the factory fill ATF+4 in there in their PS Systems and Manual Trans with a Synthetic version of the Specific Fluid for that system and got better performance.