It shouldn't be hard to come up with Dana 44s. For the rear, Scout II or '86-'90 Grand Wag work well if you want it to be centered. The '80-'86 Grand Wag HD AMC 20 is also a good choice. These choices all have a centered diff though. If you want an offset rear to match your Dana 18 look for '74-'79 Wagoneer Dama 44 rears.

For the front, the easiest thing to do is to get a '74-'76 Wag front end and cut the long side of the housing down by about 3.75". The job is not hard. People have done it with chop saws, sawzalls, band saws and even a circular saw with a metal cutting blade. There's an article on this in the Jeep tech section under axles. Send the long side inner shaft off to Moser or Dutchman and they'll shorten it for around $55. You can make the outers either 5 on 5.5 or 6 bolt by using either F150 or Wag rotors if you have the '74-'76 Wag or Chevy disc brake spindles.

If you're going to upgrade, you might as well do a decent upgrade.