I've never actually had a tape measure on either of them, but I don't think there is any difference in the width of the transaxles, the overall width difference comes from the rear wheel width/offset.
For the front axles, the Narrow Frame front axle and spindles are a lot narrower than the Wide Frame front axle and spindles, if the correct wide front wheels are installed on each, the overall width ends up being almost the same, because the wheel offsets are reversed between the two.
Not sure if any of this answers your question or not.
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