You can safely download the official "Android 5.1.1+" version from APKMirror (owned by the same team as Android Police). Look for the variant labeled nodpi and version 24.xx.xx . Do not download any "extra" or "modded" versions.
It respects your hardware, squeezes another year of usability out of it, and reminds us that not every Android story needs a graveyard ending. Google Play Store Apk Download For Android 5.1 1 Extra
: The current version is crashing or not auto-updating correctly on Android 5.1.1. How to Download and Install You can safely download the official "Android 5
You may also see references to version 5.1.11 , which was a major update back in 2014 that introduced the "Material Design" look . Where to Safely Download Google Play Store Apk Download For Android 5.1 1 Extra