It's possible the castings of the gearboxes are narrower. VFC gearboxes are quite wide in some spots.
I'm just theorizing, but it's possible that the gearboxes from some manufacturers are thicker due to reinforcements to help combat that front end cracking in v2s.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.