There is not a lot of information regarding the 379X floating around. As you probably know, some Japanese only models use this last. Subsequently, some factory seconds stayed ashore and are available from at least one US Alden retailer. The Japanese distributor describe this as the "military" last used for US military officer's dress uniform shoes, i.e. a particularly comfortable last for the military personnel. I am not sure how much of this is marketing hype vs. truth. In any case, IMO, I will describe 379X to be similar to the Modified, but overall smaller. The 379X has high arch support, but less so than the Modified. Volume around the toe box is smaller. For the same number size, I found the 379X to be quite a bit tighter than the Modified and Barrie. Hope that helps.