Hi
the problem in your script is that your command " return {mass:1842, steering:2.0, steering_ecf:60, centering: 1.6, centering_ecf:20};" you put it before load_sound_command...return command means it exits the init_chassis function before it ever gets to the load_sound commands.
The return command needs to be the LAST command in init_chassis function like so :
//invoked only the first time the model is loaded, or upon reload
function init_chassis(){
....
this.add_wheel('UAZ_PU_W_FL',wheelparam);
this.add_wheel('UAZ_PU_W_FR',wheelparam);
this.add_wheel('UAZ_PU_W_RR',wheelparam_Rear);
this.add_wheel('UAZ_PU_W_RL',wheelparam_Rear);
return {mass:1842, steering:2.0, steering_ecf:60, centering: 1.6, centering_ecf:20};
//sounds
_starter_sound = this.load_sound("diesel-engine-start.ogg");
_engine_sound = =this.load_sound("diesel-engine-idle.ogg");
_stopping_sound = this.load_sound("diesel-engine-stop.ogg");
_sound_source = this.add_sound_emitter("UAZ_Engine",1);
this.set_interior_sound_attenuation(0.15);
return {mass:1842, steering:2.0, steering_ecf:60, centering: 1.6, centering_ecf:20};
}