The chance of earning one of each item:

T1 Truck = 38%
T2 Truck = 31%
T3 Truck = 23%
T4 Truck = 8%

1 Star Truck = 36%
2 Star Truck = 30%
3 Star Truck = 24%
4 Star Truck = 8%
5 Star Truck = 2%

Each box contains 1 item