All XJ front axles will bolt into a TJ with no modifications. '96 - '99 XJ are the best years to look for. They don't have the shaft disconnect and do have the same knuckles and u-joints your '04 has. Prior to '96 they had the smaller u-uoints but you can use your current shafts. Go back a few more years and you get into things like the shaft disconnect and a two piece knuckle. They did come with 3.55, 3.73, and 4.10 gears.
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