ATS - 18-20 Speed Transmission V12.0 (1.42.x)

Update v12:
- Added support for Rezbilt389

This mod features an 18 and an 20 speed transmission that’s made for heavy loads and efficient hauling.
The differential_ratio for the ultra transmissions is: 2.83
The differential_ratio for the transmissions is: 2.94

Authors: Rc FlashDriver, trainguy_gaming