It seems to vary from system model to system model. Sometimes Dell will include all necessary adapters/cables/brackets/interposers to simplify future installations that the end user will want to perform, and other times they'll only include those items if they're necessary based on the way the system was ordered from the factory. In that case, your best bet is probably to contact Dell Spare Parts rather than looking in the normal online sales channels. I'm not sure what would happen if you bought an HDD directly from Dell since I've never done that for laptops. However, I've done it for servers, and in that case the hard drive comes with the caddy that's meant for the server you're ordering the drive for -- but in that case the drive is also specifically indicated as being meant for that server model.
Welcome to the Dell Community @Maximas200
If the Interposer board is not included it is available.
Interposer board part PRW9D for $9.99"
Agent (TIP_Sabrina V): "Unfortunately, not all spare parts are viewable on-line since we have another internal and restricted sales tool we are using.
I did not have your "Service Tag" so I just used your model number.
It would be best if you would check to make sure it is available???
Dell's chat has helped me many times.
I hope they can help you.