During promotions like this, the reciept will show a "maximum return value" for even the free items.
I think it works like this,
3 piece kit = 348
Truck = 99
Other tool = 168
Total value = 615
The truck's value at regular price is a about 16.1% of the total value.
16.1% of 348 (because that's all you're paying for with the promotion) is $56.03.
So if you returned everything except for the truck, you'd get all of your money back except $56.03.
Maybe someone can correct me if I've got it wrong.