Considering most class 8 trucks in the 70s were offered with dozens of engine options from many manufacturers, the T-series seems a bit lacking with only the Gavril TCX. This Engine pack changes that, featuring 4 engines, including two stroke diesels, as well as a few transmissions for the T-series.
Added parts include:

    V8 and V12 two stroke diesels (with custom sounds from @Semi_Sound_Doctor ,and custom model)
    2 I6 modern turbodiesels (with custom sounds from @Tronadorous)
    10, 13 and 14 speed manual transmissions
    6 speed automatic transmission
    12 speed DCT transmission