Can you Swap parts between different Alienware laptops?

Hi I have an older 17 R4-4K laptop.  I neen to get some basic ribbon lock caps for a few of the ribbon connectors.  I am a bit concerned if I buy a used (17 R4-2K, 17 R3, 15 R4, etc) instead.... that the internel parts would be too different, thereby spending hundreds of dollars on "useless parts?  Is this anything to worry about?

Thanks, Maka