Peterbilt 379 Engine Sound mod

This mod includes new Engines, Sounds, Transmissions and fixes for the original sounds of this truck.

New Engines:
– Cummins Signature
– CAT 3406
– CAT 3408
– Detroit Diesel Series 60

New + adjusted transmissions:
– Eaton 18 speed with 4.1, 3.91, 3.65 diff ratios
– Eaton 13 speed with 3.71, 3.55 diff ratios
– Eaton 10 speed with 2.65, 2.10 diff ratios

Fixes:
– Fixed Jake Brake of the original engines to work on v1.22