While V5.9 was built for 1.45, newer versions (like V6.5) have since been released to support game versions 1.50 through 1.53.
If you'd like to find the download or see more recent updates: ETS2 SCANIA RS 2016 DOPLNKY V5.9 1.45
“You can buy and set up truck accessories yourself in the workshop, or you can buy a ready-made truck from a dealer.” Steam Community Technical Notes While V5
Adds numerous new attachment points (slots) to the front bumper, roof, and side skirts to allow for high levels of light and accessory stacking. While V5.9 was built for 1.45