The Postal III Unofficial Patch (also known as "Lazlo's Postal III Patch", and as "Postal III: Non-Director's Cut" by it's creator) is an unofficial patch made by Lazlo to fix some of the faults of Postal III.
While the Source Code remains lost (thanks Akella), Lazlo (former sound designer for Whackjob Interactive, currently independent modder) has taken it upon himself to create a script-based patch (as nothing in Postal III is compressed/encrypted) to make the game better. The first version of the patch was released in December 2016.
As the last official patch was V1.12, Lazlo's patch continues this with the current patch being V1.13.
Eventually, late in March 2017, Lazlo would pull the patch from MediaFire, citing his reasons as having "borrowed" (read: taking without credit) too much from the Postal III Improvement Mod.