I had exactly the same thing happen with Amazon TWICE now. Second one is going back and I'll find one somewhere else that is complete. Only difference was my boxes were in good shape and no rips or damage anywhere.
my second one was the same, just a shock and not a complete package. the good thing is amazon took it back, paid all the shipping and refunded full. still sucks big time that they dont have the complete package.... probably gonna go thru DeeZee EZ down tailgate lowering assist kit they dont list ours, but if you call them they usually give a discount for calling in orders, and can verify the part# as the one everyone has used.