Because of your low speeds, 4.56 or 4.88 would be a good match, in my opinion. 5.13 might be a bit much IMO. I don't think you'll have problems with it breaking, since you don't have low range (not 4x4?) .The ring teeth are smaller than 4.88 but the teeth that break are usually the pinion teeth, and it looks like 5.13 gears do have thick-cut pinion teeth. But your transmission is kinda dumb, and it might spend more time shifting between 1 & 2 than actually using 1st gear. You'd probably have to re-spring the valve body, so that it'll shift quicker. Might not be a bad idea with any ratio above than 4.10.
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2000 E450 dually V10 wagon
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