hmmm...
in my 84-86 catalog I see:
3.07, 3.31 (gas sipper package!), 3.54, 3.55 (with a different part number than 3.54... wtf), 3.73, 4.10, and 4.56.
87-90 I see:
3.07, 3.54, 3.55 (wtf), 4.10, 4.56
91-93 I see:
3.07, 3.55, 3.73 (ZJ only), 4.10
94-96 I see:
3.07, 3.55, 3.73 (with diesel), 4.10
they even have different gearsets depending on whether it's RHD or not. Not sure why.
97-99 I see:
3.07, 3.55, 3.73 (turbodiesel), 4.10
some weird info in there and I am sure the factory put things together strangely sometimes, but there just isn't a 4.56 ratio available in the XJ catalog after 91. If I had to bet, it's because 87-90 they used an AW4 with a special bellhousing and torque converter for 2.5/autos while in 91 they went to a 30RH or a 32RH or something.