One field with multiple values?
This is likely to be a many to many relationship. 

create table drivers (
  driver_id int primary key,
  ...
);

create table trucks (
  truck_id int primary key,
  ...
);

create table drivers_trucks (
  driver_id int references drivers(driver_id),
  truck_id int references trucks(truck_id),

  primary key (driver_id, truck_id)
);