yup, perch moving is very common. just remember that XJ perches and MJ perches are different widths apart too. don't just weld new ones directly under the XJ ones. MJs are 42" center to center.
I'm a bit late but I went through and edited out the common reused codes this morning. sorry, but you don't have rack and pinion steering or a powdercoated rear bumper. lol
3.73 gears is by far the most common ratio in the Libertys. great if your truck is 2wd, but 3.73 is one of the least common ratios in MJ/XJs so finding a front axle with it can be a challenge. fortunately 3.73 is common in ZJs and TJs and those axles bolt in.
be sure to add some basic tidbits about your truck in your signature.
paint codes will be on the metal tag on the firewall towards the drivers side.
the list we get from Chrysler is both incomplete and problematic. your full code list will be longer (because a lot of info was lost by AMC way back when before chrysler got it into their computers) and filled out more accurately (chrysler has since reused some of the codes and so now the original meaning is lost to us).