A new BlackBerry OS 10.3.1 build has leaked out today, but the build number might surprise you. OS 10.3.1.1298 has appeared on BlackBerry Production servers, which is seems to be far behind OS 10.3.1.2072, which we saw a few days ago. What is surprising is that this build is rumored to be the one that will launch on AT&T BlackBerry Classic and BlackBerry Passport, so is it quite possible that BlackBerry is developing two distinct branches of builds (AT&T-specific vs others).
Links for the new 10.3.1.1298 .bar files are out for all the BlackBerry 10 devices so if you feel strong enough in your sideloading capabilities, feel free to do so but remember, BlackBerryOS.com holds no responsibility if something goes wrong. You are sideloading to your phone on your own accord and you alone are responsible.