Here's what I do when I check for "compatibility" issues:
1) Fire up google
2) Search for a site that sells the part in question (AC Compressor in this case)
3) Put in your vehicle information
4) Write down the part #
5) Start changing the vehicle information (I6, 4.7L, WJ, XJ, TJ, etc)
6) Check if part # is the same -- if it's the same, they are compatible
For better results, try this on multiple sites. If they all agree, it's unlikely for them to all be wrong.
You now know what engines/vehicles to look at when looking for a used part.
93 ZJ with tube