I would compare the u-joints of the two drive shafts just to make sure you are not working with some kind of an after market deal. then Just make sure that the slip yoke on the "new" DS is not too compressed or extended and it "should" bolt right up. I would venture a guess that the inch difference is where the slip yoke is at in its travel.
1989 XJ, 5spd, np231 with bjconversion SYE , re3.5, 33x12.5r15 BFgoodrich ATS, D30 F, Dana 44 from 87 with 4.56s, Custom front bumper.
94 yj: stock everything and 4 angry squarrels under the hood.