The generic "Army Pattern" varies depending on occupation, so even if you find a good fit, you'll likely have a lot of modifications to make to bring it in line - cuffs, shoulder boards, stripe(s) o nthe legs and so on.
In addition, mess kit is generally tailored - so "XL" isn't sufficient. You need to match height (too tall can be shortened, but too short can't usually be lengthened), girth, arms and legs...
All to say: you need a few more details to identify a good match.