>>6698242>GM III has a fairly different shape than its previous two generationsI really don't see it, unless you're talking about how it's rounder. Feet and ankle armor are obviously the GM II's, calves are the GM II's but slightly rounder and with new thrusters bolted on, thighs noticeably rounder versions of the GM II's, and the waist and torso are also noticeably rounder versions of the GM II's. Arms and head would be completely new molds, but the backpack could be diverted from the Mk-II and the hands are the same as on the GM II's.
Also
>>6698681, the 2.0 GM and its GM II derivative aren't nearly as angular as their lineart here. All Bandai really needs to do is make a new head, shoulders, and calves, then toss in a Mk-II backpack. The real question is if there's enough demand for them to do that,, and even among GMs the GM III is admittedly not a very popular suit.