I seem to remember from doing the ratio conversion on round track race cars that there is a different spacing of the flange on the carrier assembly where the ring gear mounts between the 4.10 and the lower-ratio gear assemblies. When we ran 4.10 and 4.56 gearsets for different-length tracks, we kept two center sections built up and swapped the whole unit. The higher gear worked better on a "long" 1/4 mile track where the distance was measured around the infield, while a "short" track was measured around the outside perimeter. There was about 100 feet or a little more difference in the straightaway length, which would allow a low-geared car to over rev.
Jerry

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