Android 5.0 Lollipop firmware for Sprint’s variant of the Galaxy S5 has been leaked out by the XDA developers community. That said, it should be mentioned that this firmware won’t run on run properly on any other version of the handset. The firmware comes with build number PVPU1BNKD.
Note that installing this will wipe all data stored in the phone, so make a fresh backup before you install the new ROM. You’ll need Odin (3.04 through 3.07) to flash the ROM, it has been rooted with Chainfire.