Since this is a community-developed tool, you won't find it in the official game updates. You can find it on reputable third-party modding platforms:
: Once active, the lowered chassis options will appear in the "Chassis" tab when customizing a Scania NG truck at any Scania Dealership . How To Install a Bus Mod in ETS2/ATS 1.57 NG lowering mod 1.40 – 1.44
the mod file (usually a .scs or .zip file) from a trusted site. Since this is a community-developed tool, you won't
Specifically updated to work with ETS2 game versions 1.40 through 1.44 . These versions introduced major lighting overhauls and technical changes that broke older chassis mods. Since this is a community-developed tool