There are only two cases that came in the '93-'95 ZJ: a NP249 full time case and a NP242 that only came in the 4.0l base model. All others got the NP249, to the best of my knowledge. If you are getting binding as you turn, that is normal proceedure for a shot Viscous Coupler (as you stated), meaning you have the 249 case. There are a two ways to resolve this problem.
1) Rebuild it
2) Replace it
#1 is fine if you think you can buy all the parts for cheap and re-assemble it yourself. Unfortunately the VC is like $700 from the dealership by itself, and if you buy a used one from a xfer case shop, who knows how long it'll last
With option #2 you have a choice of going with a privately owned case (I highly recommend) and a wrecking yard case (not such a great idea, IMHO, unless you can tear the case down and ASSURE that everything works BEFORE you buy it).
Personally, I'd look around the for sale section on Jeepsunlimited.com and see if anyone upgraded their 249 to something else BEFORE it started giving them trouble. There is also www.jbconversions.com
who can get you a NEW 231 case for $800. George at Transfercases Unlimited in New Jersey is a huge help as well. JU has a plethora of info, so make sure to check that site out before you start in.
Good luck to you!!!