Kojak, YJ's are leaf spring. No airbags for that application that I'm aware of. Air shocks are the only option.
If you're only looking for load compensation, and we're talking about camping gear, not filling the back with gravel, the stock shock mounts will be OK assuming they're sound. I have a friend who ran air shocks on his LandCruiser for years and loved them. Hopefully you can still find some for a YJ, as they are phasing them out of production it seems...
As pointed out above, if you're trying to level a constantly sagging rear, longer shackles would be the cheapest way to go, and would work fine. If you carry heavy a lot, adding a leaf to the pack is more work, but would add some capacity in addition to a little height. Just use a full length leaf, whether an aftermarket one or one stolen from some other spring pack. If you can find a set of take-off YJ springs, just cut the eyes of the main leaf and add that to your current pack.