The 400 series is more stout than about any thing on the market in my opinion from a build stand point. That machine design can trace its DNA back to the XT series designed in the mid 90's. Steel was cheap and they used a lot of it on those machines. They became expensive to build as steel became much more expensive. Everyone has done the same thing over latest generation of machines, Takeuchi seems to be the exception to building lighter. Look at CAT's C series loader arms verse the D series. I think most have taken a "build smarter" approach on their newer machines which means using more engineering and less steel.